Subject: Solr8 changes how security.json restricts access to GUI

I got your screenshot ( <>)

This is quite uncommon. You should see a loging screen if you have basicAuth enabled.
Have you tried a different browser?

What do you get if you run this command

curl -i http://your-solr-url/solr/admin/info/system

Or if you use your browser’s developer tools to inspect network traffic?