https://chromium-review.googlesource.com/c/590569 has your @google account in the reviewers list. You are viewing your review dashboard with your @chromium account.

There are two ways to fix this:
1) Ask the owner of the change to not add your @google account to reviews; or
2) Link your accounts (see https://polygerrit.appspot.com for the pros and cons of linking accounts)

I explicitly requested to unlink my @google.com account for other issues. 

This now sounds like a usability issue. I never had this issue with rietveld. Is there a way for Gerrit to prefer @chromium.org accounts in the reviewers list and/or prevent duplicate display names?

You're right that it is a usability issue, but it isn't a regression. You may not have, but plenty of other people did -- there are untold hundreds of folks whose *personal gmail* accounts are in Rietveld because they accidentally signed in That One Time.

The way to prevent displaying addresses that you've signed in with but don't want to use is to link them to your primary account.

> The way to prevent displaying addresses that you've signed in with but don't want to use is to link them to your primary account.

Admins also have the ability to mark an account "inactive", which causes it not to show up in autocomplete: https://gerrit-review.googlesource.com/Documentation/rest-api-accounts.html#delete-active

Unfortunately that's not self-service: https://gerrit.googlesource.com/gerrit/+/74fa7b74b1c9cf3d2d7df4c556701c94aef8ce53/gerrit-server/src/main/java/com/google/gerrit/server/account/DeleteActive.java#49