I’ve owned just about every larger iPad since they were introduced. But I started buying iPad Pros in 2015 with the first 12.9”. So I don’t think so.
Anyway it’s not important now as long as they don’t do it anymore.
The 2015 12.9" is affected by the Apple SIM locking so it was probably that.
Yeah, carriers really shouldn't have the ability to lock devices that the customers paid full price unlocked from other stores. It's good they don't do it now but I wish the same unlocking rules as iPhones would apply to iPads purchased through carrier (fully unlockable on both eSIM and physical SIM after payoff).