I don’t think IP addresses federate? I think only your instance admin can see your IP address. In any case, though, you should generally always assume that your up/down votes on any service are recorded and tied to your username. If you can come back later and change your vote, that vote is tied to your username. It may not be visible to other users, but the server admins can absolutely see what you’re doing.

Reddit might not make your votes publicly visible, but they’re absolutely tracking them and using that information to select what you see, including advertising. They might not directly share those votes with advertisers, but they almost certainly are sharing your interests based on your votes. And you should assume Reddit and others will comply if the government comes asking for what users liked a post the government opposes, or who downvoted a post praising a new government initiative.

It depends on your threat model, but your threat model might change. Freedom of speech might be curtailed by politicians even when that’s supposed to be unconstitutional. What might be safe to do online now might become unsafe in a year or two.

YSK: every action you take online, even as simple as an Upvote or Like, might be recorded and may come back to haunt you