So for my add-on, I decided to add custom blocks. For one of the blocks, I gave it the tag 'diamond_pick_diggable', 'stone', and 'metal'.  Which is supposed to make it to where that block can be mined faster. However, upon entering the world to test the block out, the mining speed when using a diamond pickaxe is still the same speed by default. Even when using the specific tag for the other pickaxes, nothing works. This bug has been around for a long time, I'm pretty sure it's been around since 1.12. However, I only listed the latest releases because I'm still uncertain about when it actually started.

I have no problems with this when using custom weapons, only with vanilla ones. So I think it has something to do with how the pickaxes and other weapons are coded.

So I was hoping that you could look into this bug because I find it really frustrating, to have to recode every pickaxe in the game, just to mine a block quicker. Could you look into it? Please and thank you.