Version 1.21.1, Java 25.
Patrix x128 resource pack, Iris, complementary shaders and many other mods, but nothing regarding inventory or look of the inventory and menu.
RoughlyEnoughItems is an alternative to JustEnoughItems, looks the same but is more lightweight.
If Flow (newest Version) ist installed, everything works fine but the Itemlist and options of RoughlyEnoughItems which should appear right next to the Inventory becomes completely invisible. Sometimes if you close the Inventory, the Itembar of REI flashes briefly.
Disable Background/Easein/Easeout in Flow-options doesnt solve the problem.
Nur sure but i think its the same for JustEnoughItems mod.