It seems YT started another attempt at blocking alternative clients. They changed something in their API and both SmartTube and Tubular (NewPipe fork) are completely broken. Apparently it started happening this past week, but we personally just felt it today.
Edit: SmartTube already has an update but still not working for 4K videos it seems. Tubular still not working but it might be due to the upstream (NewPipe) is still working on a fix.
Freetube is broken. It only works if you use the Invidious API, but the FreeTube API is broken at the moment. They created a fix, but it did not reach me yet on the Flatpak / Flathub version.
Freetube does work; it simply requires you switch to the Invidious API or have “Fallback to non-preferred API on Failure” enabled. (which honestly you always should have this setting ON).
Personally; I refuse to change my preferred API; so the “Fallback to non-preferred API on Failure” just works.
also yt-dlp does work but you need to upgrade to latest nightly/build.
yt-dlp version nightly@2024.07.09.232843 from yt-dlp/yt-dlp-nightly-builds [d2189d3d3]