The website https://pluto.tv does not play more than an 1hour when using FF 86 on a Mac OS, sha256:ac678174a4d7b3db70da94bdec7d54b3fa96db3e756d584c5a7d1cf09ca65a12. The symptom is it will play the video then the screen goes blank after about 1 hour and there is a cursor moving from left to right continuously at the top. I have cleared cookies through preferences and through web developer with no effect. I believe the cookies remain in effect because only when I close the FF browser and reopen does it recover. I have "delete cookies and site data when Firefox is closed" When I use another browser there is no problems. Is this a cookie problem why does play back recover when FF is closed and reopened?