I can confirm both issues with Firefox 83 on Linux: periodical auto logout and the warning message browsing external URLs. For the latter I thought it was a configuration change by the administrator.
Furthermore I report another longstanding bug: the arrows to paginate inside long threads (with more than 40 posts) always go to the first page of the same thread. The only way to change page is to click on the down arrow to the right of "Last »" button and manually insert the wanted page number.
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>-8 Live long and paper \\//_
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