theymk 3laykum salaam.
There have been some corrections over the years, but not 3000. I am sure they too have made corrections over the years. It also matters what you are comparing, as there are many uthmani editions and variations on tanzil.net, too - https://tanzil.net/download/.
Not sure what you are using to compare, but there aren't many tools out there that can compare Arabic with tashkīl correctly, if any. If it was the case, we would just be performing an OCR scan of a printed Qur'an and running with that.
If you feel comfortable using the edition you got from tanzil.net - you should use that.