Here's some very basic concepts that all leftists need to know, lest they get personally offended by basic terminology:
A settler colonial state is a state founded from a settler colonial society. This means that settlers came and conquered the land and formed a new society ....

in its place, with themselves in power and the prior inhabitants marginalised, if not outright genocided/enslaved. Settler colonialism is an ongoing process, so most settler colonial states are still settler colonial states today.

Thus the dichotomy: settler (coloniser) / colonised. These societies are run by and for the former, through structures designed by and for the former. You still benefit from and perpetuate these structures even if you aren't literally doing the initial settlement yourself.

These are not the only distinctions: for example, there are also people forced to move against their will such as slaves, who are obviously not settlers. There are also 'arrivants' - refugees, people displaced by imperialism, etc, who cannot be equated with settlers.

Settler colonial states are in any decent left circle considered to be rightful Indigenous land. This does not mean that the should be given back and everyone else is going to be forced to leave, it's rather a challenge to the settler colonial power structure.

There is no 'end date' when settler colonialism starts and ends. There is no 'end date' when people stop being settlers and start being Indigenous, at least not until the very nature of this regime is challenged & dismantled.

That you are a settler is not an insult unless you take it as one. It is merely an accurate label. It does not imply that you have no right to live there and should be forced to leave or die.

If you do fear that, though, well, you're simply projecting the anxiety that what happened to Indigenous people may happen to you. That means that you understand it perfectly - you just need to realise it and stop trying to make it about you.

Also, this should be implied from the rest of the thread, but European nativist racism is not remotely the same thing as acknowledging the very different colonial relations in places that were literally conquered and genocided, many of them by said Europeans.

A good hypothetical example to illustrate what we're talking about here: if the Nazis had, say, managed to negotiate a settlement and annexed Poland, carrying out their desired genocide of Jews, Slavs, etc, and replacing them with settlers...

Obviously, this would be an ongoing process. The German control of the land would be illegitimate. Even if they hypothetically reformed and became a liberal democratic society, this 'German Poland' would still be a settler colonial enterprise built on genocide.

What I just described is very similar to what happened throughout much of the Americas and in the USA.