I can’t say I know enough about the topic to have formed an opinion on whether or not reparations would be justified or not. But here is a point I’ve seen made that has stayed with me

While it’s true that none of us actively participated in colonialism, we still continue to profit by it. Many businesses were founded by money made in the colonies or by wares imported from them, many institutions grew by exploiting and stealing from the people living in them. At the same time the people in the former colonies still suffer from the consequences.

It’s a bit similar to calling for the higher taxation of rich people. Often they inherited their money and huge parts of it were made by exploiting poorer people, which is why it seems unfair to many (including me) that they should give back something to society. Some of my ancestors made good money owning a colonial goods store and I’m sure I owe at least part of my privileged situation to this money. I can understand that the descendants of the people who laboured for these goods might not think that that is fair.