You can use add-ons like Certainly Something (I don't know the name of an equivalent for Chromium but I bet there is one) to show you exactly what's in these certificates.

By far the most likely cause of an error like this (in which the browser clearly connected but didn't like the offered certificates) is that an intercepting proxy aka a MITM or middlebox is between your browser and the remote site and it fucked up.

Things that are intercepting proxies (some of which you might have classified wrongly as something else)

* Most 3rd party AV "solutions" or "endpoint protection" on your machine itself

* WAFs

* Any kind of "Next generation firewall"

* Government or ISP "filters"

All these products are pretty bad, and most are worse than useless. Recommendations to get one or more of them for "security" are probably this era's "Rotate passwords every 30 days" in terms of the actual security behaviour that results as distinct from what the policy proponent imagines will happen.