How big is your father? It could well be a safery issue if he is becoming agitated and aggressive ie hitting, pinching etc maybe its sk two can hold has hands/redirect his hands so he doesnt hurt staff?
4 does seem a lot though.
Can you go snd see for yourself how agitated he gets
The rule in sen school I work is less staff as its more dignified for the child. Generally we manage with 1 member of staff physically there and always another member of staff in earshot/close by for safeguarding of child and adult.
Dementia is such a cruel disease and can be incredibly hard.
Do you know what they wre doing to support his anxiety, to look at why he is so agitated.
Also I can say feom experience it can be quite tricky with men and hairy scrotum etc to ensure cleanliness ie with a messy poo. Are they needing to showr gim or use a bidet type device. Lots of options for ensuring cleanliness in a dignified way but it is not always of jobs. I worked in a residential home for the elderly.
You dont say if you father is continent, just needing support to go toilet or if he has issues snd needs pads etc
I would be inclined to try snd support yourself and see what is going on. Are you able to visit in person regularly do you know what they mean by agitated? Details of the behsviour woukd help.
But you are right to be concerned sadly not all care facilities proivide the best care, staff are often poorly trained and paid.