I'm also a huge believer in open source. I'm using Infinity for Lemmy right now but I gladly paid for the ad removal in Sync. It genuinely is the best Lemmy app out right now. It just works and has so many customization options. Not to mention, since Sync uses Google for ads, when you remove the ads, the ad component isnt initialized so you remove the tracking. So nothing to worry about there either. 20$ lifetime for such an awesome app is totally fair for me. That's my opinion, you are free to disagree.
I used Sync for Reddit since alpha (back when it was Reddit Sync), so I gladly paid the $20 ad removal, even though I also happen to be juggling both Sync and Infinity right now. They're both so good.