[leumon]

Maybe this is just some niche use-case, but I tested it with a 268x98 png screenshot, and it made the image bigger and worse: https://files.catbox.moe/7so3z6.png

[LeFantome]

JPEG is for photos.

For a white screen with black text, PNG is also compressed and less lossy.

People should not be using PNG for images. If they are using PNG properly, converting to JPEG is a mistake.

[johnnyApplePRNG]

Fair point.

Tiny, high-contrast UI screenshots are a worst-case for JPG—size can grow and edges get mushy.

PNG is the right choice here.