For the second one, Lemmy has left where it was (on imgflip), but for the first Lemmy has copied it to ls.buckodr.ink/…/859a4fd5-901b-45de-9c6c-81aadb41… (OP’s instance), so it works if you view from there, but doesn’t from viewing from anywhere else (like startrek.website)
I don’t know what the rules are for why Lemmy does or doesn’t copy an image, but the same has happened to me:
Left on catbox.moe: lemmy.world/post/4228270
Copied to Lemmy: lemmy.world/post/4409633