Well you know I have to choose who I believe as well. The problem is you got a lot of people who claim to have seen this movment performed for years before it was ever dubbed Romanians. Jim Smytz claimed to have named it at his workout center in 1990 after seeing a Romanian lifter do it. Others have also claimed to have seen it years before and some of them named it too
From what I can gather one big thing is you never fully straighten you knees. They stay flexed at around 15 or a little more degrees. They don't flex anymore or less at any point in the movement. A lot of people will do simultaneous knee and hip extension at the top of the ascent but it is supposed to be a hip thrust alone. The thing in question is if it was ever "locked out" at the hips or it the torso was always slightly forward.
I actually do both versions, locking out and not locking out. Not locking out slows the movment down but it focus a lot of back endurance and endurance overall. Locking out allows me to do it a little bit more on the strength-speed end of things because I am not slowing down the bar as much. This is just my personal take. In general I would remind people to always fully lock out their deadlifts! And in general, classic or not, I'd rather fully lock it out and contract the glutes...for my main way of doing it. And do the non lockout kind as an alternate version to work on endurance more.