4 points
Yeah but instances are supposed to e.g. delete posts when the user deletes them. A malicious instance might not do that.
The Internet Archive or archive.today might keep them as well.
2 points
Yes, but that is less likely if they have been deleted very soon after creation.
3 points
Deletions have to propagate. Comments I deleted immediately after posting them still show up hours later for people on other instances. Archivers and crawlers have as many opportunities to record your deleted comment as there are lemmy instances federated to where you posted it.
