I just stumbled across this document online, which is a long and boring read, but does have some interesting information in it. It is a summary of City's first appeal to CAS last year.
https://www.tas-cas.org/fileadmin/user_upload/Award_CAS_6298_internet.pdf
In section E paragraphs 99-109
It appears, when AC Milan appealed a decision by UEFA's Adjudication Chamber (AC), UEFA argued that Milan should have appealed to CAS after the decision was made by the Investigation Chamber (IC) to refer the matter to the AC. Then Milan complained again, and at its discretion, UEFA relented and allowed Milan to appeal.
So because City has had its appeal against the decision to refer the case to the AC rejected by CAS, UEFA cannot make this argument again. I think this is the real reason why City lodged the original appeal. So in some respects they won.
There are a few other points in the above document that we can take to heart. Firstly, CAS seems to accept the argument that UEFA did not follow its own procedures properly in paragraph 68, and is puzzled by the denial that any leaks came from the IC in paragraph 114.
It is also apparent that UEFA's scope document (paragraph 62 & 63 ), detailing what City were being investigated for was not shared with City until
28th July 2020, after the investigation had concluded. So how could City participate in the investigation or defend themselves?
UEFA argued all along that CAS should dismiss the appeal because no decision had been made, but they did not present any arguments against City's, such as the events being time barred, and the procedural ones.
It is also very clear that the evidence presented in this appeal is very relevant and will be considered in the appeal against the ban.
Whilst UEFA 'won' this time, I think City have taken the initiative in this matter and will be in a stronger position because of the points made by CAS.