I don't get the point of this.
Since when did Sync masquerade itself as FOSS?
Just use whatever you want. Isn't that why we're all here?
Is the Sync noise getting to you? Just ignore it. It's natural since the app just opened up and there were a significant amount of Reddit refugees that badly wanted their app back.
I actually got a notice like this several months ago even before YouTube did theirs.
If anything, Facebook's quite infamous for trying to combat and blockers in general. I remember back then when they obfuscated their web layout so much that it got tricky for some to filter or block sponsored or recommended content.