Seems like I am bad at hitting buttons 😄
When one clicks right of the login button (e.g. on demo.matomo.org) on the desktop page the mobile sidebar appears once. (Tested in firefox and chromium)
(Would be nice if one could upload videos to github, converting a 37KB video to a 4.7 MB gif is quite inefficient)
I guess that area is meant for touch devices so the menu opens when swiping from the side. Are you using a device with touch screen?
It’s a normal notebook without a touchscreen.
I haven’t looked into what is causing it.
It is likely a builtin jquery/materializecss feature