I’m no expert, but reducing something as complex as a whole country’s economic outlook to just the variable „immigration“ seems like an oversimplification to me.

Two things:

* developed countries obviously develop slower than developing ones. Is easier to improve if your economy is shit especially if you join a union of more advanced countries.

* polish immigration actually skyrocketed recently since Russia invaded Ukraine. It didn't harm employment, safety, growth rate or anything else yet.

2025 GDP growth for Poland is projected for 3.2 to 3.8%; for Ireland it's projected to be 10 to 11%. Poland's unemployment rate is up in 2025 from 2019, Ireland's is down. Poland's crime rate remained relatively constant in the period from 2018 to 2021 at .71 per 100k while Ireland's dropped over the same period from .81 to .44 per 100k.