Last I checked, JPEG XL takes a lot of time and resources to encode (create) an image, if you actually want it to be far more optimized than JPEG.

I think it is also a kind of “you did a nice thing there, so I’ll act as if I can do the same” display.

Tip: you can also protect yourself from other group chat users leaking screenshots of your hateful comments - just don’t be an asshole, it’s not that difficult.