I've got a couple of friends that left London to go back to Poland during covid. They first continued to work remotely, but ended up switching to Polish companies because the pay was better.
I switched from a Polish company to a German one (both remote), but my pay is more or less the same. The difference is that in Poland to get that money I have to be a "top performer" with a lot of stress and not a lot of time, while in Germany I can be just a mid dev.
Yes I think salaries are still a bit lower, but the gap has closed a lot. And cost of living is lower in Poland plus there is some tax break for self employed contractors that means you only pay ~20% tax compared to ~40% in the UK.
With those two factors you could easily end up better off overall, especially if you have kids