Okay, so apparently while I was not watching, Tesla silently increased the price of the charging. Previously there was a price table for the entire EU, usually an equivalent of 0,25€/kWh. Now, the price varies wildly country-by-country, and even supercharger-by-supercharger. For example:

• In Finland, the price ranges from 0,33€/kWh to 0,39€/kWh (the 250kW Huittinen supercharger).
• In Slovakia, the price ranges from 0,29€/kWh to 0,34€/kWh.
• In Poland, the price is a fixed 1,40PLN/kWh (0,31€/kWh as of today 7.6.2021).

There was no update or anything; the original price list simply vanished from the Tesla pages and you can only see the prices from within your Tesla car’s nav system - you can’t see the prices at the Supercharger Map nor anywhere else at the tesla.com pages.

I mean, sure, those stalls and the accompanying battery and electronics are definitely not cheap, so a price increase is to be expected to cover the costs. Still, I’d expect the price list to be transparently available on a webpage somewhere, and not completely hidden and only available from the car’s nav system.