I have never heard about Note 20 Ultra getting black dots, and your experience alone, doesn't make it the worst. Take it to a service center and get the display replaced. It can happen due to a plethora of reasons and it seems like user fault to me.
I don't agree. I am still using it and I bought it on its launch day in 2020. I did not face any issue till date. This is my third Note and fourth curved edge screen phone. In case of any difficulty, I have till now found service centres very competent. I do agree that cost of parts is too high. I had to get my screen of Note 9 replaced, it came for 19,000/-.
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