Abrowser https issue? (and broken security warning)

When I try to access https://tehnoetic.com with Abrowser, I get an error message "Warning: Potential Security Risk Ahead" (actually, my message is in French but by searching on Mozilla website, I found that this is probably the English version of it).

Clicking on "Learn more" goes to https://trisquel.info/en/wiki/connection-not-secure which gives a page saying "The page connection-not-secure does not exist." Is that a problem that I can fix in Abrowser settings, to link an existing page either from Trisquel or from Mozilla?

Besides, looking at security information, the certificate seems ok but there is a message saying that data are not ciphered. With ungoogled chromium from guix, there is no warning at all and it says everything is secure. Is something wrong with Abrowser here? Is Abrowser not able to use cipghered transmission, unlike ungoogled chromium? I remember having exactly the same situation with other websites but I can't remember which ones now.