A weird window appeared on my smartphone this morning

[Android Central Question]

Hi all!
I have a smartphone with Android 7.1.1. This morning I found a strange window with the following phrase: "ams1-mobile.adnxs.com would like to access your location". Obiously i clicked on the deny option. What's that? I scanned my phone with Clean Master, Malwarebytes, Zemana, Avast and AVG but none of them reported the presence of malware/virus. Do you suggest a factory data reset?
Thank you in advance!!

 

[B. Diddy]

Welcome to Android Central! It's probably related to an ad network: https://www.theguardian.com/technology/2012/apr/23/adnxs-tracking-trackers-cookies-web-monitoring. Adware isn't technically malware, so that's why it probably doesn't show up in those scans. Try uninstalling apps one by one to see if it goes away. Focus on games, especially if they're free and seem to be associated with lots of ads.