Here is my honest opinion now:
The main suspect seams to be the free IAP feature. This feature is always risky on server-sided games and not always available to mod. It does seem to be a soft ban because I did some tests. I deinstalled the mod, redownloaded it from the playstore and it worked. I could start a new game and then install the mod apk over it. I did not receive the connection error message (which I received with the old mod apk profile too).
So, I removed the free IAP feature and just have freeze currency and the multiplier, as well as the ad features init. I also wont make the multiplier higher bc x10 is good enough.
Please uninstall the previous mod, install it fresh from the playstore - create a new profile with it. Then you can install the mod version again. I hope that will help. Also, remember to play carefully with mod features, especially in server-sided games. A ban is never avoidable in any situation..