so, this is what was happening, apparently.

and, that's a fairly recent thing.

there doesn't appear to be an active chromium-for-xp fork to use as a backup, meaning i need any alternative to chrome to both have tls 1.2 and be xp compatible, in addition to being html5 compliant. vivaldi 1.0 is the last xp version, and it's not tls 1.2 compliant. uc might be useful for xp, but i'm a little apprehensive about downloading a browser from china, still.

so, it seems like the best back up still remains chrome - spyware and all.

https://www.ghacks.net/2019/10/02/tls-1-0-and-1-1-deprecation-chrome-to-display-your-connection-is-not-fully-secure-warnings/