I’m not home to verify my Freetube however, I just checked my invidious instance and can confirm that the first video I attempted to play errored.

I am updating my Invidious instance to see if it still persists, perhaps the instances you’re using are out of date, I know invidious updates quite frequently to stay on-top of YouTube changes.

Edit; Updating invidious appeared to resolve my errors, I can only assume the instances you’re using are out of date. I’ll check Freetube when I get home.