I found all of the prior Lemmy apps to either be missing something, clunky, or buggy. The one I liked most was Voyager/Wefwef, but even then it was missing stuff.
Now Sync is in beta and has bugs, but thanks to past development from Reddit it's already so much more polished than all the others, my Lemmy usage has gone up considerably, I've barely touched Reddit today. It does have ads, but they aren't visible when using DNS Adblocking.
Basically, whenever you make a request to access something from the internet (say, an ad image), it goes to a dedicated server that tells you "Where actually do I find www.website.com" (the answer is, you find it at address 128.129.130.1, this is the IP address). This is the DNS server.
If you tell your phone to use an ad-blocking DNS server - Instead of "normal" ones like e.g. those provided by Google - , whenever it receives such a request to find the address for you, and the address leads to a server that serves ads, it tells you, "Sorry, nothing found here" and the add is not displayed.
Phones, at least Android, have a setting where you can change the DNA server to an ad-blocking one (a different IP of that server).