The Visual Studio Code (https://snapcraft.io/vscode) is marked to be MIT, whereas the installed binary is actually proprietary! Although there exist MIT licensed source code, it has nothing to do with the installed Snap. Who should change it? How to report a bug?
The very page you linked to on snapcraft.io tells you the publisher is Martin Wimpress (who happens to be @Wimpress here), and gives you a prominent "Contact " link going to https://github.com/snapcrafters/vscode/issues.
what I would suggest Martin do, is go to his publisher dashboard and properly set the appropriate license there, so store results reflect the correct value
If https://github.com/snapcrafters/vscode/blob/master/snap/snapcraft.yaml were modified to build from source, rather than from the Deb, then it would be MIT… I think? Microsoft imply in https://github.com/Microsoft/vscode/issues/5458 that their in-house snap (which I can’t find on the store even though Tyriar refers to a snap ‘published by’ Microsoft) is built from source, rather than from the Deb, so a Microsoft-published vscode could potentially be MIT, depending on what the
snapcraft.yaml of that does.