Why did my previous post and replies suddenly disappear?

Also, if you reply to a post that has been removed, then yours will be removed as well and you will not get a notification since it was not your post that violated the TOU.

If a post gets removed while you are typing your reply, you will see the message that your post cannot be saved because the post you were replying to has already been removed.

Hello~ Posts that don’t conform to the ToU agreement may be removed in these forums.

~Katana-San~

... it said your comment cannot be saved right now, and when I refreshed the page it just proofed and disappeared…

That sounds exactly like a forum bug, not something you did or did not do. If a post is removed for cause, you get an email from the mods stating a reason. It will go to the email address you use to sign in here.

Mornings seem to be a bad time for the forum software. I often get log-outs or strange behaviors early in the day and then everything is fine.

For threads you authored, followed or participated in, you can see the last ~three months in your Subscriptions:

Reaction66’s Subscriptions - Apple Community

Note the "Filter" function at the top the list. It helps.

For older posts you must rely on a site-delimited web search from your favorite search engine. Your search string would be:

site:discussions.apple.com "Reaction66"

👉🏻 NOTE: there is NO space between the colon (:) after "site" and the "d" in "discussions."

Anyway, I think it likely that you were "bug-bit," not targeted for something you did.