I’ve occasionally seen my Mac get into a weird state where dozens of random services all want to re-authenticate. The popups appear as fast as I can dismiss them (either with or without providing credentials). This usually happens if the Mac has been running for several weeks without a logout or reboot.
The only solution once it gets into this state is to reboot. If the popups pause long enough to request a restart from the Apple menu, I prefer to do it that way. But if that proves impossible, then I will have to perform a force-power-off (long-press the power button) and then power-on after 30 seconds. At which point, it all goes back to normal.