Manjaro install to usb from a dual boot system messing up grub

Hey everyone, I am new to this forum and to manjaro and still getting used to its nuances. I installed manjaro on a pendrive with about 120gb storage with a 30gb partition for it. It was from a live usb on an Asus TUF 505dy which had a dual boot system of windows and manjaro. After the install on booting to manjaro it enters grub rescue instead of grub menu. No problem with booting to windows. I fixed it by reinstalling grub. Why does this happen(Plus the usb doesn’t boot for some reason)?

What does efibootmgr show?

It works. But I had to reinstall grub.