Hey, still a very nice looking plant.
Quiet in here, maybe some vacations, so hopefully someone better comes along.
I'd agree with the chomping, and some serious sucking.
Closest I could find to your first few images:
https://www.deltadawngardens.c... using "yucca white spots insect" on google images.
Seemed like a good article but I just glanced and am not vouching for them, haven't encountered this myself..
That said, they seem to be tying this pest Yucca Plant Bug (Halticotoma valida) to soil conditions after being root-bound. Might be worth a read.
Sorry I can't be more helpful but this seems like a possibility.
