Basic point, I installed Ubuntu on a dual-boot with Windows because I wanted to shift away from Windows but then got tangled up in the Grub 2.06 fiasco so now I decided to download EndeavourOS on another partition. Problem is, I’m still taken to the Ubuntu grub bootloader, and neither the UEFI or the Ubuntu Grub bootloader recognize the new operating system.
Did you go into your Bios and set to boot from endeavour?
Also make sure secure boot is off.
Welcome to the forum @ifgyebtu388
Ubuntu grub does not handle Arch-based distributions well. Check out this post.