Prusa Mk3S, great print followed by disaster, what's wrong

[Bobslay]

Hi,

Can someone please share their opinion on the failed prints in the attached photos. I have spent hours tweaking z offset, temps and changed nozzle and cleaned the printer but I am still struggling. I got the successful phone stand you can see in the photos but for every one of those I'm getting 20 that don't even get started. I have tried with and without bed adhesion, I clean the bed with detergent before each print (I didn't on the two pics but the fail happened on a clean part of the bed).

I'm hoping that someone which much more experience than me will look at these and be able to give some advice as I am just constantly tweaking thigs and I think I am making things worse half the time.

Also, even though I have run the config several times and run the z-offset each time there appears to be more squish on the right side of plate than the left (that may give a clue as to what's wrong).

Thanks in advance