Latest version requests permissions to delete browsing data. Why proxy management software would do that?
Please move that function into a dedicated plugin and use only necessary permissions in each.

UPDATE:
I'm not worried about a plugin stealing my data. I just don't want to have a bloated do-it all plugin, that uses permissions it does not need.

I agree, that different contexts when using different proxies may be useful, but that is supposed to be done with https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/contextualIdentities and not with data deletion. Even then, it's probably a scope of a different dedicated plugin.

I would also like to point out, that if you decide to remove browsing data access later, it will be a removal of a well-used feature (and much more users will come yelling), while now it is an addition of an unnecessary quirk.

To be less negative, let me say it in a different way. I adore the simplicity of previous version, with a little bit of UI polishing it would easily become my favorite plugin. Please don't take that true quality of a dedicated tool from us.