What I did instead and works is add this to my platformio.ini environment
platform_packages =
toolchain-gccarmnoneeabi@~1.90301.0
That made it install 1.90301.0 just fine and everything compiles as well. I am guessing the effect is the same as the manual install you describe @maxgerhardt? Thank for the help on this, and good to know it’s been fixed in dev. I can totally live with a workaround until that makes it to a release.