It's not an unofficial version of the app. It is the actual app. It's just that you have to sideload it, which is an unofficial way of obtaining the app.
Some people have legitimately gotten the app off the Play store, which would indicate that either Tesla or Google is doing a rolling release. Someone who already has the app can pull it off their phone can upload it to a mirror site so others can sideload it instead of waiting for it to appear "officially."
Here is the apk bundle for 4.1.0 (download it on your phone):
Tesla 4.1.0-663 (160-640dpi) (Android 6.0+) APK Download by Tesla, Inc. - APKMirror Free and safe Android APK downloads
www.apkmirror.com
And here's an app you can use to install that:
APKMirror Installer helps you install APKs and apkm, xapk, and apks app bundles
play.google.com