Normally I set GRAALVM_HOME to my downloaded GraalVM installation which currently looks like: /Users/borkdude/Downloads/graalvm-ce-java11-21.2.0/Contents/Home. Since Big Sur I need to apply sudo xattr -r -d com.apple.quarantine to the GraalVM installation to remove the quarantine attribute. But this does not work when you pass include Contents/Home: pass the part without it, like:
sudo xattr -r -d com.apple.quarantine $GRAALVM_HOME/../..
or
sudo xattr -r -d com.apple.quarantine /Users/borkdude/Downloads/graalvm-ce-java11-21.2.0/Contents/Home