16.05.1 >> 17.0.2 Additional Settings menu disappeared

Recently upgraded to 17.0.2 and when I went to set dark mode for the browser app the Additional Setting menu disappeared and instead I only get the digit ‘1’ appearing in the area reserved for the menu options.

I’m getting this same issue after the upgrade from Nextcloud 17 to Nextcloud 18. Is this a known bug? No error or warning is shown in the logs, but when I access the “Additional Settings” menu, the content area only shows the “1” digit: