diff --git a/core/src/com/unciv/logic/city/IConstruction.kt b/core/src/com/unciv/logic/city/IConstruction.kt
index a3b75d11a9..c4e34ae863 100644
--- a/core/src/com/unciv/logic/city/IConstruction.kt
+++ b/core/src/com/unciv/logic/city/IConstruction.kt
@@ -27,16 +27,16 @@ interface INonPerpetualConstruction : IConstruction, INamed, IHasUniques {
     fun postBuildEvent(cityConstructions: CityConstructions, boughtWith: Stat? = null): Boolean  // Yes I'm hilarious.
 
     fun canBePurchasedWithStat(cityInfo: CityInfo?, stat: Stat): Boolean {
-        if (stat in listOf(Stat.Production, Stat.Happiness)) return false
+        if (stat == Stat.Production || stat == Stat.Happiness) return false
         if (hasUnique(UniqueType.CannotBePurchased)) return false
         if (stat == Stat.Gold) return !hasUnique(UniqueType.Unbuildable)
         // Can be purchased with [Stat] [cityFilter]
         if (getMatchingUniques(UniqueType.CanBePurchasedWithStat)
-            .any { it.params[0] == stat.name && (cityInfo != null && cityInfo.matchesFilter(it.params[1])) }
+            .any { cityInfo != null && it.params[0] == stat.name && cityInfo.matchesFilter(it.params[1]) }
         ) return true
         // Can be purchased for [amount] [Stat] [cityFilter]
         if (getMatchingUniques(UniqueType.CanBePurchasedForAmountStat)
-            .any { it.params[1] == stat.name && (cityInfo != null && cityInfo.matchesFilter(it.params[2])) }
+            .any { cityInfo != null && it.params[1] == stat.name && cityInfo.matchesFilter(it.params[2]) }
         ) return true
         return false
     }
diff --git a/core/src/com/unciv/models/ruleset/unique/Unique.kt b/core/src/com/unciv/models/ruleset/unique/Unique.kt
index fab428c929..75b4473d8d 100644
--- a/core/src/com/unciv/models/ruleset/unique/Unique.kt
+++ b/core/src/com/unciv/models/ruleset/unique/Unique.kt
@@ -157,7 +157,7 @@ class UniqueMap: HashMap<String, ArrayList<Unique>>() {
     }
 
     fun getUniques(placeholderText: String): Sequence<Unique> {
-        return this[placeholderText]?.asSequence() ?: sequenceOf()
+        return this[placeholderText]?.asSequence() ?: emptySequence()
     }
 
     fun getUniques(uniqueType: UniqueType) = getUniques(uniqueType.placeholderText)
diff --git a/core/src/com/unciv/models/ruleset/unique/UniqueType.kt b/core/src/com/unciv/models/ruleset/unique/UniqueType.kt
index 17860e7da0..790454f85e 100644
--- a/core/src/com/unciv/models/ruleset/unique/UniqueType.kt
+++ b/core/src/com/unciv/models/ruleset/unique/UniqueType.kt
@@ -190,8 +190,6 @@ enum class UniqueType(val text: String, vararg targets: UniqueTarget, val flags:
     BuyUnitsByProductionCost("May buy [baseUnitFilter] units with [stat] for [amount] times their normal Production cost", UniqueTarget.FollowerBelief, UniqueTarget.Global),
     BuyBuildingsByProductionCost("May buy [buildingFilter] buildings with [stat] for [amount] times their normal Production cost", UniqueTarget.FollowerBelief, UniqueTarget.Global),
 
-    @Deprecated("As of 3.17.9", ReplaceWith ("May buy [baseUnitFilter] units for [amount] [stat] [cityFilter] at an increasing price ([amount]) <starting from the [era]>"))
-    BuyUnitsIncreasingCostEra("May buy [baseUnitFilter] units for [amount] [stat] [cityFilter] starting from the [era] at an increasing price ([amount])", UniqueTarget.Global),
     
     // ToDo: Unify
     EnablesGoldProduction("Enables conversion of city production to gold", UniqueTarget.Global),
@@ -624,6 +622,9 @@ enum class UniqueType(val text: String, vararg targets: UniqueTarget, val flags:
 
     // region DEPRECATED AND REMOVED
 
+    @Deprecated("As of 3.17.9, removed as of 3.19.3", ReplaceWith ("May buy [baseUnitFilter] units for [amount] [stat] [cityFilter] at an increasing price ([amount]) <starting from the [era]>"), DeprecationLevel.ERROR)
+    BuyUnitsIncreasingCostEra("May buy [baseUnitFilter] units for [amount] [stat] [cityFilter] starting from the [era] at an increasing price ([amount])", UniqueTarget.Global),
+
     @Deprecated("As of 3.17.10 - removed 3.18.19", ReplaceWith("[stats] from [tileFilter] tiles <after discovering [tech]>"), DeprecationLevel.ERROR)
     StatsOnTileWithTech("[stats] on [tileFilter] tiles once [tech] is discovered", UniqueTarget.Improvement),
     @Deprecated("As of 3.17.10 - removed 3.18.19", ReplaceWith("[stats] <after discovering [tech]>"), DeprecationLevel.ERROR)
diff --git a/core/src/com/unciv/models/ruleset/unit/BaseUnit.kt b/core/src/com/unciv/models/ruleset/unit/BaseUnit.kt
index 3ba88f2d25..5f14819e95 100644
--- a/core/src/com/unciv/models/ruleset/unit/BaseUnit.kt
+++ b/core/src/com/unciv/models/ruleset/unit/BaseUnit.kt
@@ -252,15 +252,7 @@ class BaseUnit : RulesetObject(), INonPerpetualConstruction {
         if (cityInfo == null) return super.canBePurchasedWithStat(cityInfo, stat)
         val conditionalState = StateForConditionals(civInfo = cityInfo.civInfo, cityInfo = cityInfo)
         
-        return (
-            cityInfo.getMatchingUniques(UniqueType.BuyUnitsIncreasingCostEra, conditionalState)
-                .any {
-                    it.params[2] == stat.name
-                    && cityInfo.civInfo.getEraNumber() >= ruleset.eras[it.params[4]]!!.eraNumber
-                    && matchesFilter(it.params[0])
-                    && cityInfo.matchesFilter(it.params[3])
-                }
-            || cityInfo.getMatchingUniques(UniqueType.BuyUnitsIncreasingCost, conditionalState)
+        return (cityInfo.getMatchingUniques(UniqueType.BuyUnitsIncreasingCost, conditionalState)
                 .any {
                     it.params[2] == stat.name
                     && matchesFilter(it.params[0])
@@ -292,22 +284,6 @@ class BaseUnit : RulesetObject(), INonPerpetualConstruction {
             val baseCost = super.getBaseBuyCost(cityInfo, stat)
             if (baseCost != null)
                 yield(baseCost)
-            // Deprecated since 3.17.9
-                yieldAll(cityInfo.getMatchingUniques(UniqueType.BuyUnitsIncreasingCostEra, conditionalState)
-                    .filter {
-                        it.params[2] == stat.name
-                        && matchesFilter(it.params[0])
-                        && cityInfo.matchesFilter(it.params[3])
-                        && cityInfo.civInfo.getEraNumber() >= ruleset.eras[it.params[4]]!!.eraNumber
-                    }.map {
-                        getCostForConstructionsIncreasingInPrice(
-                            it.params[1].toInt(),
-                            it.params[5].toInt(),
-                            cityInfo.civInfo.civConstructions.boughtItemsWithIncreasingPrice[name] ?: 0
-                        )
-                    }
-                )
-            //
             yieldAll(cityInfo.getMatchingUniques(UniqueType.BuyUnitsIncreasingCost, conditionalState)
                 .filter {
                     it.params[2] == stat.name