GLACIER Ok, I have updated into the current release branch, but need to do some tests. The reason this was not updated earlier, is because CodeMirror 6 branch originally only released ESM modules , so there was no standalone resources ... It seems this has been amended with latest release 6.65.7. New release should be out in 4-6 weeks time.
What I'm not convinced about, they did not reply with any specific issue link to your report? Have you even tried a working CodeMirror 6 demo to make sure it works in new version on your device/browser? I can't find any other issue reported on Github specifically with what you have reported.