https://migrationobservatory.ox.ac.uk/resources/briefings/the-labour-market-effects-of-immigration/
Where do you think economic growth even comes from? It comes from labor! All of the value in the economy is created by labor, literally nothing would exist if it weren't for working people doing their jobs. Then, those same workers who created value with their labor are paid wages, and then they spend those wages to pay for food, housing, utilities, clothing, entertainment, etc etc.
There's a reason so many countries are panicking about low birth rates. Population growth is critical for economic growth.
By the way, you're the one making the claim that "both are bad" - why don't you have to show me a study or something to back up your idea?