I guess it's differs quite a bit between specific countries, but where I live (which is pretty close to as far east as you can get without leaving the EU) that might had been the case a couple of years ago, but now 60k pre tax is not at all an exceptional salary reasonable for a senior developer (I'd around 80k is close to the upper bound). And the living expenses are not even close to the more expensive W. European cities, you can get a fairly decent 2 bedroom apartment in a relatively good area for below 200k.

To be fair the gap between senior developer and entry level salaries is pretty big here. Entry level salaries might around 30k (which is close to the median overall full time salary here if you live in the capital).

I personally know multiple senior devs in Poland doing multi-year contracts at 110-130k eur per year. In Western Europe, with their skillset, they'd probably get just 20-30% more, so the gap is closing even at the top end of the market.

Eastern Europe,or at least some parts of it, already seeing tech salaries getting closer to those in western Europe,while cost of living is still fairly reasonable.