I've filed a bug report with the developer: https://github.com/nls1729/acme-code/issues/81 And I'm updating my RPM package to mark Do Not Disturb Button v39 as incompatible with GNOME 40. Hopefully the upstream has a fix before Fedora 34 / GNOME 40 is out of beta.
In that GitHub issue, upstream developer Norman L Smith says he's discontinuing Do Not Disturb Button, so I have retired the package, as of commit 321dfafe4e.
*** Bug 1938438 has been marked as a duplicate of this bug. ***
*** Bug 1941006 has been marked as a duplicate of this bug. ***