There's an option on Mastodon which prevents you seeing the same boosts again and again in your timeline.

The option is on by default, but unfortunately it is hardcoded to allow boosts to repeat after 40 other posts, which is way too low for many people.

There's a suggestion on the Mastodon github to allow people to set their own number after which boosts can repeat, so that they can reduce repeating boosts. If you're comfortable using github, you can vote for this at https://github.com/mastodon/mastodon/issues/18693