Apple suddenly requiring me to change iCloud password

Today I noticed that in BusyCal the dates for US Holidays (iCloud calendar) weren’t being displayed, even though I could see that syncing with iCloud was still occurring for my other calendars. So I tried to log in to iCloud on my MacBook (Catalina, 2 factor authentication is on), and upon submitting my password I got an overlay message telling me to “Choose a stronger password.”, with a field for verifying my current password first, and icons at the bottom for Find iPhone, Apple Pay and Apple Watch Settings.

It appeared that I was partially logged in though, because the links to my iCloud account and iCloud apps/settings were available at the top of page, but going to them showed everything with a lock symbol except "Find iPhone”. On the iCloud settings page, all the links to “Verify your identity” were disabled, clicking them did nothing.

There’s been no changes to the iCloud account that I’m aware of (my son bought songs on iTunes just last night), and neither myself nor my family (2 others) are receiving notices on any device about needing to re-enter or to change the password or a warning that someone may be attempting to log in, your account has been locked, etc…. And the current password already meets the requirements listed for a new password.

On both the MacBook and on my iPhone I’m still logged in to iCloud because I can update apps and various settings and preferences all show as being logged in. My AppleID screen in system preferences shows me as logged in to iCloud and I get no prompts there about changing the password.

I was using Firefox initially, so I tried Safari on the MacBook and when I entered the password using the keyboard I got the “shaking” screen indicating a wrong password, but when I used 1Password with TouchID, instead of “shaking” I got the same “Choose a stronger password” screen as on Firefox.

But… using Safari on my iPhone I could log in using my current iCloud password with TouchID. How does that make sense?

I could have just chosen to change my password the first time I saw that message, but I’m suspicious enough that especially without any other indication or warning as to why I’m being told by Apple that I HAVE to change my password (had never been told that before) with no other option, that after Googling it and coming away with nothing concrete, I thought I’d run it by the better minds here.

Should I contact Apple about this, or despite the couple of oddities I mention, does this match up with anyone else’s legit Apple experience? (if so, Apple needs much better messaging/explanation of such things!)