Hi Luigi,
Please read some of these posts. They discuss the Avast antivirus issue.
Your app is not infected; it is just probably that your app is not in Avast’s database. On some phone devices (namely Huawei and Xanomi I believe) the virus checker is provided and updated by the hardware developer. These devices either do not update its virus signature or finds you are an ‘unknown’ developer and the heuristic virus checker flags your apps as having malicious content. Yes, erroneously. Do we know this for sure? No, because generally Huawei doesn’t talk about it and Avast listens and makes changes (in some instances) that white list the suspect app without explaining why it was black listed in the first place.
Follow the advice in the posts… contact Avast and Huawei etc., describe the problem and complain. Several developers have gotten Avast to white list their apps.
In my opinion, it is NOT related to the use of reading data from a web database through an external php file.’
Good luck.
Regards,
Steve