This has the same security implications for the user upgrading from the deb to the snap, but not new snap users. You are right to point out that upgrading from the deb to the snap would be a major regression when the passwords are no longer available (which is a different story than a new user who is using chromium for the first time where chromium could more naturally guide the user). This seems to strike the right balance, though it is probably best if: a) the connection happens in a way that the user can discover (eg, echo for each connection) and b) this should only happen on upgrades, not apt-get install of the deb (which installs the snap).