every time i try to apply a texture pack that changes the appearance of axes/shovels/hoes/pickaxes/swords it bugs out. as if the vanilla texture are governing what actually shows up. like i have a texture pack that turns all swords into salmon, but instead of turning them into salmon they are bugged sticks of pixels
If the texture inside that resource pack looks different (assets -> minecraft -> textures -> item), it could be caused by custom model of tools. Try to turn off every resource pack but this one. If it works without any other pack, it is probably because different pack modify model of those items. If it doesnt work, I would look to assets -> minecraft -> models ->item, if there is something modifying it. If there is nothing and you have optifine, I would look to assets -> minecraft -> optifine, if there is something that modify it.
As you shown just broken textures in minecraft, there is no way for me to know what could be wrong, so I just written some options that I know of.