PNGs now get converted to jpg

Not long ago I could upload png images in my attachments and they would stay in this format and keep their transparency.
But now they get converted to jpg and lose their transparency.
You can see it here. I edited the first post and uploaded a newer version of the image but I didn’t edit the second post.

Why is that ?

Not sure. I’ll look into it.

Oh, it’s because I was trying to upload 16-bit pngs. I converted them to 8-bit and now it works.

Whew… that makes sense then.