The US has had relatively steady population growth for so long, all our normal ranges for economic indicators have an assumption of a growing population baked in, including what a healthy amount of GDP growth is - enough to both cover the prior GDP per person for the new people, and also have some productivity growth.
This year with all the immigration policy changes (and maybe some emigration pattern changes), projections are for a population decline. Which means potentially GDP could maintain or slightly improve on a per-capita basis, and yet decline overall.
The current policies are doing damage that will last at a minimum of decades, but I think it’s important to try to sort out the real damage from the weirdness of massive change. If we manage to get a majority of elected officials who actually want to do repairs, good analysis will be important to figuring out best bang for resources to focus on.
An economic podcast I listen to has covered how much foreign investment the US net trade imbalance has led to, for exactly that reason: foreigners had dollars from US entities buying more stuff than they sold, those dollars had to come back to the US, and investment ended up being a huge way that happened. If the trade imbalance actually reduces, likely that investment rate will be the first thing to drop. We’ve already seen hints of it with softened demand for Treasury bonds.