I have a 2023 Crosstrek, my wife has a '21 Ascent. I have the same habit you do - edging away from large trucks slightly - and both of them do the same thing you described to me.

It's essentially that Subaru's lane system actually has two levels: it has lane keeping where it's just trying to keep you inside the lines, and then on top of that it also has lane centering which is pretty much what it says.

Just a note for you or anyone reading who has a recent Subaru and doesn't know already: if you find the centering really bothersome, you should be able to be able to go into the settings on the instrument cluster display (up/down arrows at the lower left behind the wheel, toggle it until you get to the "hold for settings" option), find the Eyesight settings, and turn off lane centering. It will still try to keep you inside the lane markers but won't try to park you right in the center of the lane. In that mode, it's more like the Honda Sensing system I had on my 2016 Civic.

I go back and forth a bit on it but mostly keep it in lane centering mode now - I've gotten used to how it positions the car in the lane, and it lets me focus more on what's going on around me than micromanaging lane position and such.