We have a near-stock Chromium 76 running on Android 7 on our custom device. Since December, we've had sporadic but increasingly common reports that users are not able to sign-in to Google properties, as they get a message about using an insecure browser. Similar to: https://www.omgubuntu.co.uk/2019/12/couldnt-sign-you-in-google-browser-error-linux and: https://support.google.com/accounts/thread/22873505?hl=en
For some users, and this is seemingly random, they get an error saying "This browser or app may not be secure." The dialog says "Couldn't sign you in. T his browser or app may not be secure. Try using a different browser. If you're already using a supported browser, you can refresh your screen and try again to sign in."
This has been reported by users with GSuite accounts, personal Gmail accounts, accounts with "less secure apps" enabled, and accounts with "less secure apps" disabled.
Is there anything we need to do in our Chromium build to ensure this works for all of our customers? Or, alternatively, is there someone at Google we could be put in touch with to see why some accounts work and others do not?
This seems to have started in December sometime.