For me it's how they inconsistently, backwards-incompatibly, make some existing characters outside of the emoji-plane (and especially when in technical/mathemat

For me it's how they inconsistently, backwards-incompatibly, make some existing characters outside of the emoji-plane (and especially when in technical/mathematical blocks) render colored by default, rather than keep everything colored related in the emoji plane (making copies if needed rather than affecting old character, the semantics are very different anyway), e.g. https://imgur.com/a/Ugi7K1i https://imgur.com/a/Ugi7K1i and https://imgur.com/a/UMppZHG https://imgur.com/a/UMppZHG