Caynax Sports tracked is what I've been using. Not for privacy reasons but because it's simple and has the features I need.
Mountain Biking
It's better when it's dirty
What features do you use? Their website seems pretty slim but makes it appear that their apps are primarily about home fitness training, not necessarily trail mapping. Being a Polish company might help as they would have designed everything with GDPR in mind, even if they’re not required to avoid invasive tracking of international users.
I like that it uses open street maps which have a way better trail coverage than google maps. However the only feature I needed was the ability to save my tracks there which helps to see what all trails I've rode on already.
Is Gaia gps any good? I'll be honest, I have no idea how it fares RE privacy, i use it to track my hikes.
Thanks for the recommendation, but I’ll have to pass on it. I’m sure Gaia GPS is great for hiking, especially with offline topographic maps, and presumably good for MTB as well. However, it’s owned by the same folks as Trailforks. They started with a bunch of venture capital in 2020 and went on a tear buying other companies in 2021 and 2022 including Trailforks, Pinkbike, and Gaia. It took a couple years for them to start enshittifying Trailforks, but now that the process has begun I have little doubt that I want to avoid giving them data through any of their other brands as well.