I run Boot-Repair just to document what is where on my system. Best to know.
Please copy & paste the pastebin link to the BootInfo summary report ( do not post report), do not run the auto fix till reviewed. Use ppa (2nd) with live installer or update Boot-Repair ISO when booted.
https://help.ubuntu.com/community/Boot-Repair &
https://sourceforge.net/p/boot-repair/home/Home/
UEFI remembers old installs, and ESP -system partition often has folders for old installs. Best to houseclean those.from liveDVD or flash booted in UEFI mode and use efibootmgr
sudo efibootmgr -v
The “-v” option displays all the entries so you can confirm you’re deleting the right one, and then you use the combination of “-b ####” (to specify the entry) and “-B” (to delete it). Examples #5 is delete:, with Ubuntu you need sudo, others must be at root. some need all 4 hex chars, others only need significant digits
sudo efibootmgr -b XXXX -B
man efibootmgr
I normally use grub2’s loopmount to boot an ISO directly from my second drive, or an external drive. I used to use flash drive with either just grub or larger ones with a full install. Now use external SSD as much faster. No extraction of ISO required.
I do now have an external drive with Ventoy and think for most users that is an easier option. Also no extraction of ISO required. Just copy to Ventoy folder.
https://discourse.ubuntu.com/t/beyond-grub-usb-stick-with-refind/67747/2