Regarding the Google Chrome browser, I use a Mac and seldom use Chrome. So for grins, I opened Chrome, logged into this site, opened a reply window, and started typing every word incorrectly. Every incorrectly spelled word was underlined in red. So, maybe it is a Windows update issue as mentioned earlier.
As a further check, I contacted my son who is a computer engineer in Google's Los Angeles office and attached a link to this message thread. His response is below. BTW, Merry Christmas to all!
"Hard to say for sure but if I had to hazard a guess: either the Windows update screwed things up or they unchecked the Chrome "check spelling" option (it's kinda easy to toggle by accident if you right click on a text box)."