How to troubleshoot ERR_CERT_AUTHORITY_INVALID error on specific site, on specific device, on specific browser?

I get the ERR_CERT_AUTHORITY_INVALID error only on a specific website, only on one Android phone, only using Chrome mobile.

• the site works (i.e. https is accessible without error) with every other device, also on Chrome mobile
• the site works on the same Android phone using another browser (tried with Firefox, DuckDuckGo browser)
• other sites work on the same Android phone, on Google Chrome

To me this indicates a sudden issue with Chrome mobile on this specific phone, on this specific site. Everything is up to date, and the site worked until an hour ago. No changes happened on the phone (i.e. new updates) that would imply a connection.

What I tried to no avail, in the following order:

• using incognito
• empty cache, cookies
• full uninstall and reinstall of Chrome
• factory reset the entire phone

Any idea how I go about troubleshooting this?

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