Do private proxy providers log your usage info like vpns do?

Someone on skype made the contentious claim to me that proxy providers on this website are 'blackhat' and so are stealing your traffic and farming your information like a tor evil exit node might.

Is he tinfoil hatting?

Maybe some of them would skim your traffic but I doubt they keep logs? like vpns do? or do they?

I am wondering since I recently found out the vpn I use keeps logs and had leaked my dns all this time so I was wondering if the private proxies I use for work (which I checked…

Do private proxy providers log your usage info like vpns do?