Fennec F-Droid is based on the latest Firefox release (codenamed Fenix). It has proprietary bits and telemetry removed, but still connects to various Mozilla and Google services that can track users.

Edit: Quickly checked an article from Mike Kuketz (german): https://www.kuketz-blog.de/firefox-datensendeverhalten-android-app-f-droid-version-browser-check-teil6/

Fennec contacts mozilla servers to get new lists for the anti fingerprinting and anti tracking technologies. Also xml files with info about vulnarabilities etc. It sends not much.

Google is contacted when you have google as standard search provider and search suggestions active.

Otherwise no tracking etc