AdwCleaner 7.1.1. I think this is a false alarm:
***** [ Firefox URLs ] *****
PUP.Optional.Legacy suggests.go.mail.ru"C:\Program Files (x86)\Mozilla Firefox\browser\omni.ja"
mailru.xml
<!-- This Source Code Form is subject to the terms of the Mozilla Public
- License, v. 2.0. If a copy of the MPL was not distributed with this
- file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
<SearchPlugin xmlns="http://www.mozilla.org/2006/browser/search/">
[skip]
<Url type="application/x-suggestions+json" method="GET" template="https://suggests.go.mail.ru/ff3">
<Param name="q" value="{searchTerms}"/>
<Param name="gp" value="900200"/>
</Url>
[skip]
</SearchPlugin>