How to Detect if your phone has a Virus
It is pretty easy to detect that your Android phone has been compromised to a virus attack. Below are the meaningful signs for you to spot if your phone has been infected by a Virus (mostly malware).

1. Battery Drainage: All of these unauthorized functions in the background will ultimately cause your battery to drain quite quickly because your phone has a virus. So if you notice signs such as a drastic drainage in your battery or your phone heating up even if you’re not excessively using it, be alarmed.

2. Excessive Pop-ups: This is one of the most obnoxious and obvious signs of them all. If you’re seeing uncalled for ads, reminders and unfamiliar system warnings, then the integrity of your phone may be compromised. This will result in slowing your phone and wasting your data. Also, you are potentially installing even more malware.
https://www.ababioblog.com.ng/2018/04/how-to-detect-and-remove-virus-malware-from-phone.html

Installing a bogus app could as well result lots of pop ads, and simply uninstalling it, would bring back sanity to your smartphone.