When in creative mode trying to access the Identity menu, the game crashes.
I think it may be linked to entities in "The Aether Reborn" mod ( https://www.curseforge.com/minecraft/mc-mods/aether )

crash-2021-07-30_01.04.09-client.txt

I have the same/a similar issue for all of the below entities:

Entities that error out and cause a crash when rendered via Identity screen:

• Flying Cow (the_aether:flying_cow)
• Sheepuff (the_aether:sheepuff)

Entities that render blank via the Identity screen:

• Aechor Plant (the_aether:aechor_plant)
• Chest Mimic (the_aether:chest_mimic)

Entities that render their model but not their texture via the Identity screen:

• Phyg (the_aether:phyg)
• Cockatrice (the_aether:cockatrice)

Sheepuff crash: crash-2021-07-30_00.19.25-client.txt
Flying Cow crash: crash-2021-07-30_00.18.07-client.txt