Fuel pressure issues after wet belt job

Hi all,
After a wet belt change I've been getting fuel pressure related faults with the car struggling to rev.

The car has been topped up fuel to half tank after being sat empty and on an angle for a week. I started the car and after it going through some air it started.
What I've noticed is when you start the car while its sat, it would go immediately into limp mode not revving over 2k revs. I get fault with EML, codes P0087 Fuel system pressure too low and P0089 Fuel pressure regulator A performance. Once clearing them and restarting the car, I am able to rev the car slowly and it seems to do ok. When I push the accelerator quickly it starts to jitter and struggle. The code P0089 comes back, but not P0087 which only comes up after its sat for some time and then restarts.
I have done the timing belt change myself, and as far as I know, the timing is fine after testing making sure all my line and marks are correct. Ive made sure the connectors for the HPFP is correct. As far as I can see, there are no visible leaks in the two pipes that go to the HPFP.
Ive taken apart the tappet and HPFP for visual inspection and it seems ok? I am out of ideas and would greatley appreciate any ideas. Ive included videos of the car when accel slowly vs fast, pics of the HPFP and some info on the readings on my scanner, for some reason I cannot see a HPFP pressure reading? It seems that reading is for low pressure pump perhaps, that drops and then climbs up when accelerating quickly.

Idle:
fuel rail pressure: ~420psi
Fuel rail pressure-low range: ~2.8v
Fuel rail pressure sensor: ~ 1.1v

2k revs:
fuel rail pressure: ~450psi
Fuel rail pressure-low range: ~2.5v
Fuel rail pressure sensor: ~ 1.05v

Fast acceleration (data taken during the blip):
fuel rail pressure: ~223psi
Fuel rail pressure-low range: ~2.25v
Fuel rail pressure sensor: ~ 0.8v

Looking online, I can only thing of these possible causes:

Either dirt /air is stuck in the fuel system, perhaps a faulty fuel injector though no codes for that

Timing could be ever so slightly off, however to the best of my knowledge ive timed it up right. Did not use any VVT locking tools, but did lock the crankshaft, crankshaft pulley, flywheel and the cams on top. Ive started the car as well and then redone the timing too, barcodes on top were still flush and the makrs i made on the belt / cam pulleys looked same as before.

HPFP faliure ? But im not sure how I could have damaged it. Was fine before the timing belt job.
Not sure how to send videos on these fourms, if thats needed / allowed ?

Would greatley appreciate any help!