idmsa.appleid.apple.com password deemed a secure risk

DEVICES: iMac Sonoma OS, iPhone 12 Pro iOS 17.7

Somewhere along, years ago, the many "improvements" to Apple ID added an isdma.appleid.apple.com (account ?) to my Apple account ID.

Today I got a security warning telling me to change the password to this idmsa.appleid because the password was a risk.

However, I don't use idsma.appleid.com. I am under the impression that my primary Apple ID sign-in on my iMac and iPhone are sufficient for sign-in and that, if I change the idmsa password to a new password, it might really screw up my use of Apple iCloud and other functions of my Apple use.

I also note that I have 2 iCloud accounts (dang!), each based on the two emails I used : the first was the sbcglobal.net email address I have always had; the second was when I eventually got an iCloud.com email address. I think one of them (the 1st) is an iCloud+.com cloud drive.

How do I reconcile all this confusion? Can I really change an idmsa.appleid.apple.com password without screwing things up? Can I, should I delete this idmsa.appleid.apple.com information?

Thanks for any clarity on this,

Shelley