Mirror prober fails to detect SSL error + 404 on a mirror with https redirection

The owner of a mirror contacted us as their old mirror is still considered valid by the mirror prober while it has been out of date for months.

https://launchpad.net/ubuntu/+mirror/lug.mtu.edu-archive
http://launchpadlibrarian.net/644234023/lug.mtu.edu-archive-probe-logfile.txt

For example the log says:
Wed Jan 4 16:59:49 2023: Found that http://lug.mtu.edu/ubuntu/pool/multiverse/f/fabric-manager-450/fabric-manager-450_450.216.04-0ubuntu0.20.04.1.dsc exists. Updating MirrorDistroSeries of ubuntu focal-updates source multiverse freshness to Up to date

While:
$ curl -fIL http://lug.mtu.edu/ubuntu/pool/multiverse/f/fabric-manager-450/fabric-manager-450_450.216.04-0ubuntu0.20.04.1.dsc
HTTP/1.1 301 Moved Permanently
Server: nginx/1.20.1
Date: Wed, 04 Jan 2023 23:41:39 GMT
Content-Type: text/html
Content-Length: 169
Connection: keep-alive
Location: https://lug.mtu.edu/ubuntu/pool/multiverse/f/fabric-manager-450/fabric-manager-450_450.216.04-0ubuntu0.20.04.1.dsc

curl: (60) SSL certificate problem: unable to get local issuer certificate
More details here: https://curl.se/docs/sslcerts.html

curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

$ curl -fLIk http://lug.mtu.edu/ubuntu/pool/multiverse/f/fabric-manager-450/fabric-manager-450_450.216.04-0ubuntu0.20.04.1.dsc
HTTP/1.1 301 Moved Permanently
Server: nginx/1.20.1
Date: Wed, 04 Jan 2023 23:44:56 GMT
Content-Type: text/html
Content-Length: 169
Connection: keep-alive
Location: https://lug.mtu.edu/ubuntu/pool/multiverse/f/fabric-manager-450/fabric-manager-450_450.216.04-0ubuntu0.20.04.1.dsc

HTTP/1.1 404 Not Found
Server: nginx/1.20.1
Date: Wed, 04 Jan 2023 23:44:57 GMT
Content-Type: text/html
Content-Length: 153
Connection: keep-alive

curl: (22) The requested URL returned error: 404

Thank you