If a third-party email app is updated, iOS 14 no longer will keep it as a user-set default, and instead reverts to using Apple's own Mail.
One of the most long-awaited features of iOS 14 was the ability to replace certain default apps such as Apple Mail, with third-party alternatives. Now, following initial problems, a new issue has emerged where iOS will automatically reset the choice of mail app if that third-party one is updated.
It seems that every time an email or browser app is updated on iOS 14, it resets the default settings.— David Clarke (@DCOneFourSeven) October 21, 2020
Twitter user David Clarke has demonstrated how accepting an update to the Gmail app meant that iOS reverts to using Apple Mail instead.
Since the iPhone was first released, there have been set default apps by Apple, which have always taken precedence over any third-party alternatives. Regardless of which app users choose, if they get a web link in an email, for example, tapping that always started Safari.