Please do note the official warnings of the BFS (Federal Office for Radiation Protection). Contamination of forests with Caesium-137 is a health risk in many southern Bavarian forests. It’s half-life period is 30 years. The disaster was in 1986. That means it’s still roughly half of it there and the layered forest grounds preserve radiation well.
If you’re a mushroom forager on vacation in southern Bavaria - just don’t do it. Or at least inform yourself which types of mushrooms you shouldn’t eat in particular for radiation reasons.
General information and warnings (2022):
https://www.bfs.de/DE/themen/ion/notfallschutz/notfall/tschornobyl/umweltfolgen.html#doc6055566bodyText3
Specifically regarding mushrooms (2019):
https://www.bfs.de/SharedDocs/Downloads/BfS/DE/broschueren/ion/info-wildpilze.pdf?__blob=publicationFile&v=7
Good.