As an outsider, but hailing from Germany's eastern neighbor and one of the largest sources of immigrants:

Overall sentiment is that the juice ain't worth the squeeze any more.

Back when my country became a full member of Schengen(2008) the ratio of GDP per capita between Germany and us was around 3.3x - salaries were roughly proportionally higher, so just about any job was worth moving there and potentially going through the hoops required to establish a permanent residence.

Earlier, especially throughout the 90s that ratio didn't go below 5, so a sizeable number of people attempted to move to Germany by any means possible.

Currently it hovers at around 2.1x and most of the discrepancy in salaries is focused on the trades.

A specialist from Poland typically doesn't have access to higher tier salaries, so they don't really enjoy a different quality of life than at home, so they have no reason to move.