"admin panel" isn't available in Samsung a3 (bug?)

I’m using my the web interface with my Samsung A3 and Firefox 65.0 (see screenshot below). In some apps the “admin menu” isn’t available. For example I cannot add a contact, using my phone with the normal default view, but it appears when using the “Request desktop site”. The issue is not available on all apps, it works fine with “Files” but not with “contacts” and “users”.

Screenshot of ok “Files”

Screenshot of contacts
– removed due to new user limitation –

Screenshot of contacts in “Desktop view”