The website that you visit (as in your Lemmy instance) does log your IP address to fight abuse etc. Afaik it's not sent to other instances, so unless the server admin sells it somewhere (which they shouldn't but I guess you never know - that's why some folks host their own instance), it shouldn't leave the server.

Obviously that doesn't mean your IP is not logged by external services embedded in the Lemmy UI you're using - be that ads, video players, etc