I asked also, & my sister-in-law (who uses Gmail) wasn't aware of any changes?

Make sure it's not you, something on your end.
In my case, Yahoo webmail stopped working.
I must have been testing something somewhere along the line, & changed my (browser) useragent setting (set it to "" actually), & when Yahoo saw that, it farted, not allowing me into my mail. Until I figured it out...