From what I've observed so far, it looks like #Mastodon wreaks quite some havoc on #Hubzilla posts with pictures in them. I guess the same happens to posts from #Friendica and servers based on #Streams.

• It probably only shows a maximum of four pictures.
  
• It moves them to the end of the post, regardless of where they are in the original post.
  
• It most likely reverses their order.
  
• It leaves them outside the summary (Hubzilla)/CW (Mastodon), so they're always in plain sight.

Here's a post to demonstrate what happens. This post should have five pictures of 7-segment digits embedded between paragraphs; vertical arrows mark where which digit should go.

↓ 1 should go here. ↓

↑ 1 should go here. ↑

↓ 2 should go here. ↓

↑ 2 should go here. ↑

↓ 3 should go here. ↓

↑ 3 should go here. ↑

↓ 4 should go here. ↓

↑ 4 should go here. ↑

↓ 5 should go here. ↓

↑ 5 should go here. ↑

If you don't see this the way it was intended, it's proof that there's still quite some inconvenient incompatibility within the #Fediverse.