I can't log in Chromium (I was a Chrome user before this, so should make another account or something)?

Solution 1:

As of 15th of March 2021, Google removed several features from all third-party Chromium-based browsers (also Chromium itself) including synchronization. Users need to either install and use Google Chrome or use alternatives (other web browsers/extensions that provide such a service).

During a recent audit, we discovered that some third-party Chromium based browsers were able to integrate Google features, such as Chrome sync and Click to Call, that are only intended for Google’s use. 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.

For users who accessed Google features (like Chrome sync) through a third-party Chromium based browser, their data will continue to be available in their Google Account, and data that they have stored locally will continue to be available locally. As always, users can view and manage their data on the My Google Activity page. They can also download their data from the Google Takeout page, and/or delete it here.

Guidance for vendors of third-party Chromium based products is available on the Chromium wiki.

Source: Limiting Private API availability in Chromium

Solution 2:

"Chrome Sync API" requires API keys.

See The Chromium Projects - For Developers‎ > ‎How-Tos‎ > ‎ API Keys.

Solution 3:

If you are still facing this problem then I recommend you to just follow these 3 steps that I followed for mine:

Go to chromium settings, select You and Google then Sync and Google Services, and then TURN-OFF Allow Chromium sign-in and then you are done.