Personally I don't like these features, but can't this official move being seen as way to curve competitors?

Especially looking at how the announcement is worded?

"This meant that a small fraction of users could sign into their Google Account and store their personal Chrome sync data, such as bookmarks, not just with Google Chrome, but also with some third-party Chromium based browsers. We are limiting access to our private Chrome APIs starting on March 15, 2021."

That I understand as "you can use the open source chromium version, but we did what was necessary to ensure that in all cases and derivatives it will be inferior to closed Chrome".

Maybe a next move could be to disable the possibility to use the chromecast from Chromium?