Weird texture bug (1.21.4)

So I've been playing with the Wynncraft Overhauled Experience modpack, which I found on ATLauncher under the Modrinth tab.
And something I've found is that none of the armours have unique textures, and some blocks seem to be getting replaced with either green command blocks or cracked Sniffer eggs.
According to the Wynncraft resource pack that came with the modpack, it was last updated on January 24th of this year, so I don't know what could be happening.
Does anyone have any idea of what could be causing this?
(Note: I originally attached two images that might've been able to help with answers, but the forums don't allow links until you've submitted ten posts)

 

Armours don't have unique textures by default, so either that's working as intended, or another texture pack you've loaded isn't working. If the latter is true, then I'd hazard a guess the official pack being updated is what broke that.