'Bin follows the same format as Mastodon for inline images, which is different from Lemmy.
Mastodon puts the details for an inline image inside an ‘attachment’ field, with nothing in the ‘content’ fields, whereas Lemmy doesn’t use an ‘attachment’ field at all for them, and includes the HTML for img src
in the content.
It’s always been the case that Mastodon didn’t show images from Lemmy comments. I don’t know if the reverse is a new thing or if it’s always been like that.
Re: your edit - please feel free to open an Issue for PieFed about it. It’s MBIN content in Lemmy’s communities, so it’s something that needs attention (we should show it, even if Lemmy doesn’t). I’ll have a crack at fixing it next time I’m working on the code.