That would be 2.2 terabytes. You are on the right track though and metric system conversion is part of the problem. 1000GB != 1024GB. 1,024GB is correct while HDD manufacturers use 1,000GB, which is also correct, but still not equal to 1024GB. (I just confused myself thinking through the conversions, but you get the idea.)

The other part of the problem is hidden partitions used for recovery or performance. There are other things like FAT and such, but I don't know the modern file layouts these days. (Its probably the same as it always was, TBH.)

The space is usually, mostly, there. It's just hidden and preallocated.

Edit: Forgot about boot partitions as well. That's a thing. Additionally, I have seen more than one instance of someone doing 1:1 drive copies without adjusting the partitions for a larger drive. That is less common these days but probably still happens.