The UI is completely bugged out when using ImmediatelyFast. Skins and inventory, mainly, though skins dont break often. I'm not too sure about mobs. I tested it out with sodium and everything worked fine.
^^^^^ Image taken in F5 mode
andreasdc commented
I think someone got IF to be compatible with VulkanMod.
Zorklis commented
Yeah it's incompatible, I think IF creator abandoned their support for Vulkan too