@gazymon said in Log out all pages and sites after Opera update. Why?:
windows 10 pro 1903 version.
There were some bugs in the 19xx versions of Windows 10 that could cause these issues in Opera and other Chromium-based browsers, especially when restarting Windows. That's all fixed now in 20H2 and newer. I would definitely update Windows to the newest. There's also a new, big update coming this month.