Attitude from my primary ages kids

Help me before I seriously lose the plot.

I feel like someone has flipped a switch in my kids and turned them into argumentative, disobedient and rude children.

They are DD(7), DS(5) and DD(2). DD2 is generally exempt as she's in the usual terrible 2's.

7 and 5 year olds have suddenly decided a week or so ago to become feral. Soaking toilet paper and sticking it to the ceiling, smearing toothpaste on the sink and toilet, pulling clothes out of my wardrobe

Making slime when I've said no (and explained why). Turned Alexa back on when I've specifically turned her off and asked them not to use her. Turning audiobook back on way after bedtime.

All fine as one off misbehaviour, but I'm suddenly being flooded with bad behaviour on all sides.

They are usually very good kids, polite, well behaved, funny. I'm on the stricter side in terms of discipline and the kids have age appropriate chores etc.

I'm definitely not soft and they definitely know better.

What the hell has happened?! And any tips to solve it.

I'm really angry, upset and frustrated. I'm trying not to take it personally but really feel ignored and like I'm being treated with disrespect.