I'm not convinced. Calibration should make some difference but HDR, if a TV supports it and is sold on that basis, needs to look decent without a load of config that only a limited number of users would know how to do. I think different TV's implement it better than others. Oh and The Mandalorian definitely has HDR issues: https://arstechnica.com/gadgets/2019/11/disneys-the-mandalorian-joins-a-long-list-of-fake-hdr-conten...
Disney+ is doing funny things though. It claims I'm getting an Atmos sound signal but my amp doesn't identify it as getting discreet height speaker signals.
Basically the streamers are using the pandemic as a basis to reduce quality (and save money via bandwidth) in ways that only techies are noticing.
It appears due to the recent Pandemic for COViD19, all Disney UK streams will downgrade the bandwitdh during this time. It is therefore possible that your set supports the 4k Ultra HD/ HDR 10/5.1 Dolby but at the moment the max you can get is HD (or even SD).
BTW I own the Samsung KS9000 TV
I Know this thread is about 4K issue for Disney+
But if you already had the latest firmware 1242 on their KS tv please take a look on this, because in fact there exists a much worse issue and bad behaviour from Samsung. Give your feedback please.