Mozilla Firefox does not want to take a screenshot of the entire page of the site, why?

Question

Browsers

If you press the key combination Shift + F2 in the Mozilla Firefox browser, then a line for entering commands will pop up at the bottom
Using the
screenshot file.png --fullpage command
The browser will take a screenshot of the entire page of the site
But here's the problem, I recently tried to take a screenshot on YouTube (nothing happened) even the screenshot preview window did not appear

spoiler

I thought because I went to the site through my account (but no - I left my account, I don’t want to shoot anyway)
Searching the network did not give anything.