Why is hearth pronounced like are th instead of like earth?

[wufwugy]

variety of dialects. mexican spanish is quite a bit different than spanish spanish

in spanish spanish ll sounds like j, in mexican spanish it sounds like y

in spanish spanish v sounds like b, in mexican spanish it sounds like v

ive even seen examples of j no longer sounding like h but instead like y

ofc it probably depends a lot where in the americas you come from