Oh dear, how many times do we see the words "I was following (satnav/Google Maps) and saw no signs" !
Anyway GSV has a confusing set of views here, but this one of September 2024, (so I assume current),
approaching the junction on Cornwall Road towards Gorleston Road/Falmer Rd shows t he usual Flying Motorbike signs, plus somewhat confusingly, No Entry signs as well !
However, it seems that you actually passed two No Entry signs before you got to the junction: -
https://maps.app.goo.gl/jJVwEB7i4xXUP5Bx5However, I may have your route wrong, so please tell us whether you drove north along Cornwall Road from St Ann's Road. There is a sign as you turn in : -
https://maps.app.goo.gl/hFL8LTthiACnAWmD8But if you're totally relying on Google I don't suppose you know anything about the street names, certainly not if you're not local. The restrictions around this area seem designed to stop rat running between St Anne's Road and West Green Road, (A504). There is stuff like this all over London now.
I'm not sure if the Billy Butcher reps are of any use, frankly. It is all mitigation, the signs are present, so you are expected to obey them. Best to never rely on Google Maps when going down minor streets ! Keep to main roads.