Sometimes the male(s) or any of the females can get a bug up their butt and bully other(s),rooster is over 2 years old. Hen is a bit over a year. I think I’ve had the same thing happen to a hen in the other flock. She suddenly started staying (all day) and sleeping in the barn with the goats, it turned out the rooster wasn’t giving her a break, but now she’s out again with the rest of the flock.
it can be minor or major, long or short term.
Best thing is to have lots of space for them all to work out their issues.
The hen I mentioned above, ended up hanging out with the group of younger birds.