There is a simple solution https://github.com/snapcore/snapd/pull/13211
But it relies on old and almost unused warnings code which may be buggy.
Also users will be required to execute snap warnings to see what is wrong.
$ sudo snap refresh
WARNING: There is 1 new warning. See 'snap warnings'.
$ snap warnings
last-occurrence: today at 11:17 UTC
warning: |
cannot refresh "snapname": snap "snapname" has running apps (appname), pids: 1374296