It should be GT.
This is the last note of anyone sending you any 'CP', which tells me it was clearly GT for a key trade. There's no newer transaction involving GT, so that's where your 20 GT is from. I can't tell what user it was from since if I click it it just tells me the user doesn't exist anymore (meaning someone that asked for their account to be deleted, like Cookie or someone), but yeah. That's where the GT is from, and it is GT.