Any response to this?

They are saying malicious redirects.
Google Adsense file is added that may redirect all sites adsense revenue to the developer. File is not deleted on removing extension. vel.joomla.org/vel-blog/2145-mobilejoomla-2-1-24-malcious-redirects

Mobile Joomla (MJ) displays ads at the bottom of our Mobile Basic template in MJ Community version (so, desktop and custom templates are not affected, as well as templates in MJ Basic/Pro version). And for this purpose, MJ appends following two string to ads.txt file:

# The line below has been added by Mobile Joomla!
google.com, pub-5710199815985059, DIRECT, f08c47fec0942fa0

These lines say Google that ads displayed by publisher with id pub-5710199815985059 are actually belong to this website (and not injected by a 3rdparty person). And it doesn't affect other ads displayed on the website.

But there is significant problem: if ads.txt didn't exist on the server, it will be created with above lines, and after that Google stops to display ads except of ones displayed by Mobile Basic template. Now we are testing an update to MJ (it will remove ads.txt created by MJ) that will be released soon. Currently the only solution is to list all publisher ids in ads.txt, and it is good idea actually. You can read more details on ads.txt at following resources:

iabtechlab.com/ads-txt-about/
support.google.com/dfp_premium/answer/7441288