A better example is Protonmail, a secure email service. It has a nice web client and there is an 3rd party desktop/electron version of the same size called Electronmail. While both essentially run identical code, the electron version is more secure because even Protonmail insert a backdoor for a single or # of users. They would have to at least publish the backdoor in the vanilla code at which point, the maintainers of Electronmail will probably raise the alarm.
[1] https://developer.mozilla.org/en-US/docs/Web/Security/Subres...