I'm from the UK too, I also get this. It's definitely to do with the age verification act that went down.
If you use a VPN and refresh the page all images will reappear. Or you might be able to create an account on the site (imgbb.com) and prove your age, then open all images under that account.
I know I know, Guvvorment is workin to make VPNs illegal but I can't see how they would manage that - anyone can build a VPN, how would they trace who is and isn't using one? (literally the point of a VPN).
Basically, we got stiffed man.
Thus begins the New Internet Revolution.