Currently :
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"Boost" adds reputation. It's a kind of retweet.
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"Downvote" removes reputation
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"Upvote" does nothing. (edit : for reputation)
This is because previously the upvote was boost, they were switched around to be similar to other fediverse systems.
Dev mentioned in another thread that the reputation system should be changed to have up/down count instead of boost/down. But they have a lot to do right now so it might not be the most pressing issue...
If you get arrested during a protest, they can force you to unlock the phone (it can be a felony to refuse) , so better not to bring it at all.