Addons/mods failing to be applied on a world displaying the word “ incompatible“

I’ve made my own vehicle mods and it’s took me over a year to create and since the 1.17 update. Every time I put it into a new world or deactivate the mod to make a change and putting it back in. I get an error box that pops up displaying the word “ incompatible“ I would appreciate to hear back off you guys regarding this issue. Many thanks