Linked Mastodon posts redirect back to lemmy.ca so can't check, but going by the intro, it's something I've been noticing, when I boost a post on Mbin, Mastodon displays as you described, at most including the image as attachment, and that despite of the original post's instance (for the thread-based ones).
Now, maybe something like what Misskey instances do would be a good solution? For example:
https://nijimiss.moe/notes/01K5T7RE2G147ZRBSZ4GDHS3NR
(For https://thebrainbin.org/m/auster_info_dumps/t/1095421)
(Just don't like the links appearing again as attachments at the bottom)