Valid concern as I use their browser often. From their FAQ (link):

I’m considering adding it to the alternatives list I posted. Can anybody else validate their privacy policy? Seemd ok but I’m a bit iffy regarding their use of telemetry. Maybe I’m overthinking it

Added

Oh for fuck’s sake! List of Firefox alternatives:

Windows/Linux/MacOS:

• Librewolf link
• Mullvad link
• Zen Browser link

Android:

• Iron Fox github
• DuckDuckGo? f-droid
• FOSS Browser? Codeberg link

iOS: ??