Or it’s a low grade “micronova” which the sun may be due for. Not enough to wipe out life on earth (if the sun) but enough to alter civilization.
We know so little about the inner workings of stars (we have good guesses, but, that’s it) that we really need to start planning on seeding the galaxy pretty quick.
For example. Delta Scorpius was a perfectly normal star up until 2000, then it brightened considerably almost overnight and has stayed much brighter than it used to be. If the Sun did something like that, life may go on, but, not for very long, here on Earth.
Space is a dangerous place.