They never said why in writing, but I was told verbally it was to "Respect international customers". It was in contravention of UK law which states it is an offence for uk businesses to enforce foreign embargo. I did try to pursue it with a UK MP when I got back, but he informed there was nothing he could do. The account was closed and the frozen funds released 18 months later, by which time my business at that time had long gone under.
I am not bitter, it isn't worth losing our sanity over. I blame the system which is starving us and the planet of energy, no individual is in charge of it, everyone in it contributes just by being part of it, and we are all locked in, no matter how rich or poor. This is how I see it, and why I've been dedicated to helping fix the energy problem since around 2017, unfunded, other than what I've been able to put towards it.