I'm guessing your DDs are Y5-Y6?
It may be hormones, but it is also frustration at neither being a little child or a teen.
I've found that a bit of control over their lives and a bit of freedom works wonders.
Doesn't have to be much. Choosing dinner, a day trip in half term, a bit of leeway on bedtime or lights out. Leaving them for 30 minutes while you take a sibling to piano.
Let them go swimming or to the cinema with a friend and no grown up. An hour on the high street or a safeish shopping centre.
I passed my cycling proficiency at 10 and was allowed to cycle to the village on my own.
My DDs walk to the sweet shop more often than they cycle, but the same idea.
Good schools give Y6's jobs and reception DCs to buddy. The teachers let them have a bit of slack, but wind them in if they abuse it.
However, even great teachers are constrained by SATs causing stress and reducing choice and variety.
Parents need to step lightly, nag for school work only if essential.
Home needs to be a balance of grown up responsibilities, hugs and childish games.
It's not always easy, but I think 8-11 year olds are, perhaps the nicest age DCs of all.
Not that DD1 isn't a lovely 14 yo.