Really? I've never heard of that. But it does sound interesting. From what I do know is that I've seen the last show finale episode and seen how the ended the show.
Jerry creates this new formula that rids the world of evil. Of course, something goes wrong (I won't spoil of what happens next) and so Jerry and the girls have to save the world again. After the problem was fixed, Jerry decides to retire from spy work - which also meant that the girls wouldn't be spies anymore since there will be no longer missions or WHOOP headquarters.
So, I'm not sure how Marathon (the company who created Totally Spies) will start off the story since the Jerry retired and that the world is free from evil - not unless there's going to be a major plot twist that brings both Jerry and the girls back into spy action.
If they do make a season 6, I'm kind of curious on how they will start the new season.
Oh, just in case if you were wondering what the name of the episode is, it's called "Totally Dunzo" (Season 5 Episodes 129 & 130).