I quite enjoy this bug in 1.12 but switching from 1.12 to 1.16 and having witch farms produce 1/3 less is pretty annoying, I don't know if this would be hard to implement, possibly just removing a check when a spawn attempt is made but I could be wrong, like with your 100% efficient witch farm using skeletons, now you can only reach 99.2% efficiency or something similar by doing an eol witch farm which isn't really achievable for most people