This is a possible solution rather than a question. I could not use Firefox to log into The New York Times website. I tried restarting and then disabling various add-ons without success. The solution that worked was to click on the tracking protection shield icon on the left side of the URL bar (see attached screenshot) and choose "Disable blocking for this site." That did the trick.
The genesis of this idea came from a comment user Fred McD made in response to a similar problem raised in 2018. That (now archived) thread can be found at https://support.mozilla.org/en-US/questions/1220343.
I'm not happy about allowing a website to track me, but I am relieved to have access to the Times. I hope this will help someone else.
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- User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:64.0) Gecko/20100101 Firefox/64.0