I have to say this could have been my mum posting about me but she wouldn't know how to and my youngest is 17 in a few days.
From my perspective, everyone took the opportunity during lockdown to clean their houses, re decorate, get into the gardens etc - my house never seems to have been messier! Myself, hubby and our 3 sons plus 1 girlfriend were all here and it was great, we have the space, live in the middle of nowhere so we're lucky to have outdoors too.... but and it is a big BUT... they all kept busy doing stuff outside - mechanics on quads, bikes, mowers etc and I just got depressed. The more housework needed doing the more I didn't do it.
It doesn't help I have cancer so am limited and am awaiting a major lung op, but I wish I just felt a bit more mojo to actually Hoover or dust or do the washing!
I'm getting better, pushing myself and everyone going back to work and the cleanliness lasting longer than 5 minutes has helped massively.
Maybe your daughter is a bit depressed - she has a 9month old and not got her mum near by, I'm guessing her partner was home/furloughed too and maybe she was digging her heels in with him too (if he wasn't helping)
I'm sorry I haven't read the full thread, I just thought it might help hearing it from someone who is battling the dreaded housework blues.
Talk to your daughter, little and often and I hope everything works out xx