start addressing the fixmes

src/main/java/net/lerariemann/infinity/entity/client/ChaosPawnTint.java

···
         else {
             color = VersionMethods.opaque(color);
         }
-        //fixme 1.21.10 this probably shouldn't be null
+        //FIXME 1.21.10 this probably shouldn't be null
         vertexConsumer.submitModelPart(part, matrixStack, RenderType.cutout(), light, overlay, null, color, null);
     }
     *///?} else if >1.21.5 {

src/main/java/net/lerariemann/infinity/mixin/iridescence/PostEffectProcessorMixin.java

···
 
 @Mixin(PostChain.class)
 public abstract class PostEffectProcessorMixin {
-    //FIXME 1.21.10
+    //FIXME 1.21.8
     //? if <1.21.2 {
     /*@Shadow
     private float time;

src/main/java/net/lerariemann/infinity/mixin/options/BackgroundRendererMixin.java

···
 
 @Mixin(FogRenderer.class)
 public class BackgroundRendererMixin {
-    //FIXME 1.21.10
+    //FIXME 1.21.8
     //? if <1.21.2 {
     /*@Shadow
     private static float fogRed;

src/main/java/net/lerariemann/infinity/options/SkyRenderer.java

···
 package net.lerariemann.infinity.options;
 
-//FIXME 1.21.10
+//FIXME 1.21.8
 //? if <1.21.2 {
 
 /*import com.mojang.blaze3d.platform.GlStateManager;

src/main/java/net/lerariemann/infinity/registry/core/ModItems.java

···
     public static final RegistrySupplier<Item> IRIDESCENT_POTION =
             registerItemAfter("iridescent_potion", Items.HONEY_BOTTLE, settings ->
                             new IridescentPotionItem(glintProperties(settings).rarity(Rarity.UNCOMMON),
-                                    //FIXME 1.21.8
-                                    //? if >1.21.2 {
-                                    4
-                                    //?} else {
-                                    /*RandomProvider.ruleInt("iridescencePotionLevel")
-                                    *///?}
-
+                                    RandomProvider.ruleInt("iridescencePotionLevel")
                             ));
     public static final RegistrySupplier<Item> CHROMATIC_POTION =
             registerItemAfter("chromatic_potion", Items.HONEY_BOTTLE, settings ->

src/main/java/net/lerariemann/infinity/util/config/ConfigGenInvocation.java

···
     public BlockPos pos;
 
     public static void invokeOn(ServerPlayer player) {
-        //FIXME - 1.21.10 height check
         //? if <1.21.2 {
         /*ServerLevel w = player.serverLevel();
         int y = w.getMaxBuildHeight() - 10;
         *///?} else {
         ServerLevel w = player.level();
-        int y = 256;
+        int y= w.getMaxY();
         //?}
         BlockPos pos = new BlockPos(player.getBlockX(), y, player.getBlockZ());
         (new ConfigGenInvocation(w, pos)).run();