Extension Menus do have a Down-Arrow by default. I guess this is a relict from the past when EasyEDA and also Extensions just had Icons in the main menu.
The Down-Arrow should be removed, it makes no sense...

Maybe also seperate Extension Menus with a vertical divider from the regular Menu items.
Chrome
89.0.4389.90
Windows
10
EasyEDA
6.4.17