It's Google Groups, which has weird behavior if you're somehow associated with a G Suite account that doesn't have Groups enabled. (My employer has some weird G Suite integration that prevents viewing public Google Docs, which has caused me to notice a few websites that are secretly just iframed Google Docs exports....) Try incognito/private browsing mode perhaps.

Do you have JavaScript disabled? Don't you know we need JS to view nearly static mailing lists with minimal user interaction in 2018? /s