Mastodon has a built-in system to prevent you seeing the same post boosted again and again. However, it allows boosts to reappear if 40 other posts have passed through your main timeline, and this is why you may see the same boost repeated.
As the Fediverse is now much busier, Mastodon's devs are raising this number to 80 other posts (technical details are at github.com/mastodon/mastodon/p…). This should hopefully be in the next update.
(Thanks to @nitrml for pointing this out 🙏 )
Change reblogs to be deduplicated within the last 80 posts instead of the last 40 by ClearlyClaire · Pull Request #39784 · mastodon/mastodon
Your self-hosted, globally interconnected microblogging community - Change reblogs to be deduplicated within the last 80 posts instead of the last 40 by ClearlyClaire · Pull Request #39784 · mastodon/mastodonGitHub
