Joint bank account - Will it be frozen if one POA activated?

So both my parents have been in a care home since June.

Mum's in the nursing wing and apart from numerous health problems is now not really able to sign her name and gets confused about all sorts of things.

Dad's in the residential section and has MCI but isn't too bad. He's able to sign cheques and worry if the newspaper bill seems to be too high (he was right).

They both have the old fashioned kind of POA set up (but not yet activated). Currently both are self funding but only for a few more months as two people in a care home is ££££s.

If we activate Mum's POA (my husband and I are the joint POA) for both of them, will the bank freeze the joint account for both of them?

Dad, in his early 90s, is not really quite ready for POA at the moment and would be very upset if his was activated. He's a retired lawyer so did their own POA in good time.

If it will be frozen, which would create all sorts of problems, then we will activate the POA for both of them at the same time which, I'm assuming would be the solution to a frozen account?

Does anybody have any comments or advice please?