I will try and keep this non-biased :D
Person A & B in flatshare.
A was originally splitting time between flat and DPs place, eventually due to the CV situation decided to spend lockdown at DPs. B remained in the flat.
Person A feels she shouldn't need to pay bills during this time as she isn't in the flat and shouldn't contribute for that reason (to internet, gas, heating). Person B feels she should, as A hasn't moved out and doesn't have plans to, once lockdown is lifted she will come back to the flat. Person A is already quite relaxed with lockdown and has wanted to pop back to flat multiple times, and so if measures were relaxed would probably continue.
For added info, person A does not pay rent/bills at DPs and has not worked for last couple of years as has wealthy family. However, she already feels it's unfair to be paying rent on a property she isn't living in currently, let alone bills on top.
From person Bs perspective, she has friends who would move into spare room if A moved out, meaning she would be able to completely split rent/bills. Person B (like many of us), is potentially facing job loss and financial struggles, so this is more of a factor to her.
Current lockdown guidelines state that genuinely moving house ("measured in days not hours") is reasonable, so changing household is still currently acceptable!