In reply to Jeroen.

Thank you @Jeroen!

You are correct. I seldom use this block, but I have been using the Custom HTML block a lot over the past several weeks using the Safari browser. I noticed in Safari’s settings under “Autofill” that “Other forms” was checked. Sure enough, the site I was working on was listed there. Apparently, Safari automatically adds websites to this Other forms as the site I’m working on has several forms. The auto spell corrections within Custom HTML block occurred the morning after WordPress 6.2 was installed on the site; so I presumed it was the culprit! (I am sorry WordPress 6.2 dev team members!). Thank you for the brilliant lead @Jeroen and @Markus Finell