It is not about how they behaved at that point in time of history. It is what do they about it since then about it.
Tens of thousands of artifacts never returned to the countries from which it was taken including Crown jewels like Kohi-noor, or how Meghan was treated, views on reparations, or preserving the legacy of empire[1] and still holding on to being head of state of so many countries and all the privileges they have fought to keep their way of life - A president does not withhold signing a law to negotiate special exemptions for his family (see Royal Consent abuses)
I don't think the UK is the only country that has items from conquered nations. It just has the most.
And given that the UK ended the slave trade, to whom should reparations be paid?
Megan was treated very well indeed, until she decided to turn on the British people and the Royal Family.
The Royal Family aren't forcing countries to keep them as the head of state. In fact she's been removed from a few I believe. Of course, a lot of the countries that are doing this are chasing Chinese money, and just swapping one "coloniser" for another.
