I read the documentation, read the forums, and can't find any kind of information in regards of DeliveryAPI Changes. I used to work with Umbraco 13, that generated a swagger file with GetContent2.0, GetContentItemByPath2.0, GetContentItemById2.0 and GetContentItems2.0, now I am starting a new project with Umbraco 16 and my swagger file has QueryV20, ByRouteV20, ByIdV20 and ItemsV20 instead. Am I doing something wrong, or is this an actual breaking change?

This might be a change to the tooling your using more than Umbraco, I know with Orval for example you can tweak the naming conventions

I am using Orval now, I used others in the past, but the problem already exists on the swagger itself. Because QueryV20 is already the operationId on the json file. And if I check my Umbraco 13 projects, all swagger json files on the same endpoints has GetContent2.0 instead. And worst it created duplicated operationIds for Content and Media... I had to create a script to download the json, make all the operationIds unique by adding their tag as ContentQueryV20 and MediaQueryV20, but still this seems to be too much F* up. Imo the problem comes from umbraco itself, need to dig this deeper.

This sounds like an issue that needs raising on github if its coming from the SWagger files

Found out the culprit, UIBuilder package. After uninstall it, all good again.