Adobe has done it again – confusing users who have been using Photoshop for years. Every time I open a fresh install, these shapes are absent. Instead of googling the answer and searching every time, here it is:

Go menu item Window > Shapes. you can load the Legacy Shapes and More.

Source: https://community.adobe.com/t5/photoshop-ecosystem-discussions/legacy-custom-shapes-in-photoshop-2020/td-p/10727508