I remember there being a case about Ubuntu spying on users via the integrated Amazon search feature years ago. They include non-free software by default, such as the Snap store, and Ubuntu is also owned by Canonical.
I'd recommend switching to Debian. It's community-based and entirely free and open source (except for non-free firmware packages, but those are not much to worry about, and you can easily remove them if you like). A new major release of Debian came out recently with many upgrades. You should check it out!
You can send a letter without a return address. I plan on taking this idea and sending it out to my neighbors who have one. It honestly seems like a fun side activity.