> Immigration/tourism requirements are always the strictest against the very countries who were plundered during colonial times
Trivially false. The UK has strict requirements for Russia, a former imperial power. The USA was formerly 13 British colonies and has few restrictions.
The USA is a current imperial power and built atop of a genocide against its native population. The US as an entity has no history that would be relevant to a historical plunder carried out by the British.
Russia is currently in direct conflict with the UK (specifically financial and indirect military support to Ukraine, obviously not with regards to a hot war). Whereas that is not the case with any African nations I am aware of, yet many of those nations face significant travel restrictions not faced by a pre Ukraine invasion Russian population.
The USA wasn't plundered as a colony.