I was investigating Proton's apps and I was thinking of starting a thread on this app versioning issue, because it seems somewhat shady.
At least until some weeks ago, Proton also released an official, signed apk from their website (here). But now, the button "Proton mail android apk) redirects to GitHub releases, where the latest available release is v3.0.17 and hasn't been updated since 17 oct. 2023! The latest commit to the repository is also from 7 months ago. Before, the button redirected to another link (this: proton.me/download/MailAndroid/ProtonMail-Android.apk), which actually downloaded one of the latest available signed apk (version 4.0.5, by analyzing it with the Android sdkmanager's aapt dump badging ProtonMail-Android.apk
command).
Other Proton apps' latest apk, e.g. ProtonPass, can be directly downloaded from the website: clicking the download button the user gets redirected to https://proton.me/download/PassAndroid/ProtonPass-Android.apk
They also removed the app from IzzyOnDroid (here is the latest available snapshot), and many years ago they promised to release Protonmail's app on F-Droid, but that has not happened. In 2019, oh their official blog, they wrote:
[...] we plan to publish our apps on a number of alternative app stores for Android. A few possibilities are presently under consideration.
First, we plan to release our apps on F-droid, an open source Android app repository, which is today one of the most popular alternative app stores.
The shadiness is increased since, as previously stated on this thread, the reported version on the Play Store is 3.0.16, but in fact the app's manifest reports the latest version (4.0.9), and is continuously updated. So how come the discrepancy? Doesn't Google Play Store recognise the app's version automatically through the app's manifest?
Moreover, the GNU GPL 3 licence, that Proronmail's Android app is based on, requires the source code and every updates to the source code to be made available, or to be provided to the user; failing to do so is a violation of the licence.
I don't know why they are not updating the public open source repositories, but I don't like this. I have opened a support ticket on this matter, but I haven't got any response.