The charm snap, used to build and release charms, will be changing to classic confinement soon. This will allow charms to be built from anywhere, allow charms to use custom build tactics which rely on external dependencies, and address some charm store login issues such as getting logged out whenever the snap refreshed.
Unfortunately, this will require a manual step if you already have the strictly confined snap installed, but you will be presented with a warning containing instructions on how to do this.
Testers for this are wanted to try moving from the beta channel (strict, with the warning) to edge (now classic) and provide feedback on the refresh process and help us spot any issues with the classic confinement in various environments.
The backstory for this is that the snap was originally changed to strict confinement some time ago mainly to address a set of issues with system-level Python libraries causing conflicts with those included in the snap. There is now a better solution for this built in to snapcraft in the form of patchelf. With that change, classic confinement makes much more sense for the charm snap due to it being a development tool which may need to access files outside of the user home directory.