I think there are various reasons hosts may be struggling.
For sure, in some cases guests are rude/selfish/violent/greedy/lazy/insert adjective here. Nothing to do with anything other than people being people and that being a refugee doesn't make you a saint.
In other cases, there are undoubtedly cultural challenges - no one is at fault but it's hard to have someone in your house doing things very differently to the way you do things. Children staying up late is fine when it doesn't impact on others, but in a household situation it's a challenge. Leaving children unaccompanied (a common complaint) is not ok here but seems very widespread in Ukraine. And while I can't see how leaving a 5 year old alone is anything other than a terrible idea, clearly it happens and (usually) everyone is fine.
And I do think there are hosts who entered into this with an unrealistic expectation of what it would be like. Doubt that has anything to do with WW2, but right from the start I wondered how those hosts who did everything for their guests, paid for everything and said "they are our new family" would feel four or five months in. My assessment of this, from various social media groups, is not great because it's exhausting and unsustainable, particularly if those on the receiving end then let you down in various ways. Or just people where you wonder what they were thinking - I'm aware of a family near here who welcomed a mother and 3 children under the age of 10 into their home, meaning there were 3 adults and 5 children in a five bedroom house with 2 bathrooms and not much living space. Unsurprisingly, this was a disaster and the Ukrainian family has had to be rehoused.
I suspect most hosts at this point, a few months in, are just a bit tired. Not desperate, not about to kick their guests out, just wanting their homes back and wondering how that is ever going to happen when there's unlikely to be an end to the war any time soon (and my lovely easy going helpful guest has said she doesn't plan on going back any time soon even if it does end - she likes it here and wants to earn money to send home and improve her English) and the prospects for most of renting in a cost of living crisis with a huge shortage of rental properties are vanishingly small. I did not expect it to be such hard work, because naively I thought support would be available. I did think that after nearly 6 months there would be some end in sight, and there isn't. I do want my home back but my commitment to my guest and my desire to make sure she is ok trump my own needs and wants, but I feel an overwhelming sense of exhaustion most of the time. And that's with a guest who is a single adult with good English, a decent work ethic and a relatively tidy and clean approach to living in a shared space.