Install gnome-shell-extension-remove-dropdown-arrows by entering the following commands in the terminal:
sudo apt update sudo apt install gnome-shell-extension-remove-dropdown-arrows
Description:
removes drop down arrows from panel on GNOME shell
Removes the dropdown arrows which were introduced in GNOME 3.10 from the App Menu, System Menu, Input Menu, Access Menu, Places Menu, Applications Menu and any other extension that wants to add dropdown arrows. . GNOME is an intuitive and attractive desktop. This is an add-on to GNOME, and will likely not be useful on its own.
Homepage: https://github.com/mpdeimos/gnome-shell-remove-dropdown-arrows
Version: 9-1
Section: universe/gnome