How many daily workings does this happen on? I've travelled in F a few times from Kings Cross or York to Hartlepool and not noticed it.As far as I am aware it’s always been the case to having seats segregated off for crew PNBs.
Also to reiterate, the 8 seats in coach F are indeed for crew to take their breaks. Given the short turn around the crew currently have it’s unavoidable to have their breaks on trains.
It’s been raised many times and I know for ASLEF they are wanting to have discussions around this but as we know nothing is a quick fix on the railway.
Personally it’s not ideal but it’s very restrictive in having alternative arrangements.