For the entertainment value, bought the new 2021 GPro.
Spent an hour matching the new racquet to the specs. Will go to the swing weight machine for exact fine-tuning, but for the first test, it was a perfect match for weight and balance. Even with that, I could feel the difference. 2021 has more weight in the throat, and 2019 has more even distribution with a bit more in the head. Few blind tests confirmed it, so there is a difference there. In the play, the difference is much smaller and almost negligible, so I am fine with that.
But are 2019 and 2021 GPro the same racquet? No, they are not. At least with two samples that I have.
2021 is stiffer, no question about it. It seems that the throat is stiffer in 2021, while the 2019 model has more uniform stiffness. If 2019 has 62 RA, the 2021 model is more like in the 64-65 range. It plays fine, could switch between the racquets easily, so at least that is good, but they definitely feel a bit different.
The paintjob finish is different also. 2019 is more smooth and glossy then the 2021 version