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
The kids factor is even bigger if you move back close to relatives. The ability to drop your children at grandma's instead of paying for childcare is an easy 1k a month you're saving.
Daycare is completely free in Poland since 2024 (you need to submit an application to ZUS, but there are no limits, it's always accepted), even the private ones. You only pay separately for food (10 zł per day the child is actually attending to the daycare).
I wtedy przynajmniej babcia będzie szczęśliwa pilnować dzieci.