The loss in rep from users being removed is almost always from upvotes being deleted (as each -10 is an upvote). This means that the posts still exist, but they just have one less upvote, as if it never happened. Upvotes are always removed when the deleted user didn’t vote much, or there was vote fraud involved with the account at some point.
Sometimes it’s pretty obvious who cast those votes, particularly when the deleted user was high rep. I think the reason why you can’t (easily) see which specific posts had votes on them is to try to preserve some degree of privacy for the votes.
There are some cases where this could cause your post to be automatically deleted, but for any of those posts, a single well-placed downvote would cause it to be deleted too.
You can see your recently created posts that were deleted in your profile, but there are only two ways that you can see all of your deleted posts:
- Get the ability to see deleted posts on a site (unlocked at 10k or 2k rep depending on the site), then search for
- Ask a moderator
Note that there’s no easy way to see which posts were recently deleted.