I am getting a Youtube sign in warning message. When I try to join to any channel while I am logged in, "Sign in to become a member" warning message appears. The same happens when I try to like a video or want to subscribe a channel. When I tried it on different web browsers (Chrome, Opera, Vivaldi etc) there was no sign in problem. While I see that I am logged in at the top right, a login button appears in the menu on the left. When I press the button, a page with a warning message opens: "405. That’s an error. The request method GET is inappropriate for the URL / youtubei / v1 / guide. That’s all we know." I deleted cookies in Firefox. I reset the Firefox browser. I deleted and reinstalled Firefox but the problem still exists. That's why I can't use the Firefox web browser. If you have any suggestions to fix this situation, I would be happy to use Firefox browser again. I hope you can help me.