Have you read past that screenshot of the code, though? It says the problem was not limited to Firefox, it seems Edge users reported problems as well. Anecdotally, I did experience that delay problem on Thorium this weekend as well. I have seen a variation of this problem almost a month ago, where sometimes the video would take a long time (like, over a minute, sometimes) to load, or often just not load at all. So I just chalked it up to Youtube having done something stupid on their end.
Have you read past that screenshot of the code, though? It says the problem was not limited to Firefox, it seems Edge users reported problems as well. Anecdotally, I did experience that delay problem on Thorium this weekend as well. I have seen a variation of this problem almost a month ago, where sometimes the video would take a long time (like, over a minute, sometimes) to load, or often just not load at all. So I just chalked it up to Youtube having done something stupid on their end.