#Mastodon's #ActivityPub inbox treats object types in tiers. Note and Question are supported directly. A second tier, Article, Page, Image, Audio, Video, and Event, gets converted to a title, a summary, and a link; content itself doesn't show. Anything outside both tiers is dropped on delivery, which is a large part of why so much of the fediverse federates as Note regardless of what the object actually is.
mastodon/mastodon#24079 asks for content to show up whenever it's present and the mediaType is supported, independent of type. Open since 2023, and as far as the thread shows, no core team engagement beyond one offhand remark that they're not happy with the status quo either.
Reading the issue text closely, it's a bit ambiguous whether it covers the drop tier or only the convert-to-title-and-link tier. I left a comment asking for clarification, since the fix looks very different depending on the answer.
If you build on ActivityPub, a comment or a reaction there is worth more than another workaround.
My impression is that #Mastodon developers have a history of being pretty explicitly uncaring about the health of #Fediverse or anything else outside of their personal views on how their piece of software should operate.
When they've been so hostile to their own users who would expect them to care about other users elsewhere on Fediverse?