I've been testing DuckDuckGo's App Tracking Protection (beta) for the past 24 hours.
Here's a small comparison between #Twitter #Mastodon and #Bluesky (with about equal usage/screen time).
Bluesky is by far the worst with almost 2200 tracking attempts.

Edit: I'd just like to make clear that this beta can be used by anyone with the regular DuckDuckGo browser app (on Android, don't know about iOS).

Twitter gets to second place with 355 tracking attempts, which I expected to be higher.
And Mastodon - using the Tusky app for Android - is the absolute winner with 0 tracking attempts, which I can't show because there was nothing to track.
@Rii_cck Rick, do you have lists of the the URLs the trackers were pinging? It would be interesting to know. I understand there are some website analytics tools that get incorporated into source, and could resemble ad trackers.