Minecraft refuses to load any resource pack or behavior pack since Copper Age update

Exactly what the title says. You can no longer access worlds with behavior packs or resource packs loaded since 1.21.111.1 rolled out. Regardless of whether it's enabled as a global pack or if it's enabled for a specific world, as long as you have an external pack on, you’ll be met with something like this screenshot of you try to access your world.