I’ve been encountering the same problem.
HTTP 429 responses almost every time anyone in my house tries to log in, since around January 11th 2026.
No matter how long we wait, it keeps saying "too many requests."
I'm in Massachusetts, using FiOS.
If someone from outside the affected area joins my server (hosted at my house), the server will frequently dump an HTML document to the output, with an error saying it couldn't deserialize a JSON response (similar to what Alex sees in the Modrinth loader).
It’s improved in that it’s not 24/7 anymore, but I’m still encountering this problem on a daily basis.
It also seems to affect the minecraft.net website when it happens, which I didn’t notice until I tried updating my skin the other day.
How in the world are the login servers down on a daily basis for a large chunk of New England for 21 days, with a bug report being open for 16 days, and … Microsoft and Mojang aren’t even acknowledging it?