I also did not see any ads, but today, I paid for ads removal nevertheless, just to support the development. I hope, Sync for Lemmy will go a long way similar to Sync for Reddit.
I've got an ad blocker built into my router, so in sync I only see the empty blocks where an ad would be. I'm still trying all the different apps, hopefully one if the open source ones become better. What I like a lot about sync is the gesture based up/down voting. Not sure if anyone else has that yet.