This issue is both platform and browser agnostic; it's happening on MacOS with both Safari and Firefox.

The logical answer is that you have your web browser set to open all new links in a separate window vs a tab. Can't guarantee this but it's worth checking.

Still noting a loss of line breaks in comments I've made this morning---along with the fact that I am STILL, more than two weeks into the new year, being "moderated" on every comment with no ability to review or modify that comment within the period between my posting it and roughly 30 minutes to an hour later, which was the typical time for self-editing.

I, too, use Safari on a Mac and I don't see that issue. I would suggest going into the preferences and finding SA's cookies under Privacy and delete them, forcing the site to install new cookies. That may fix the issue.