MacOS/Debian10 dual boot- how to delete unknown EFI partition?
You have two EFI partitions. Only one has the correct boot files. The other does not. You can try renaming a folder in the first EFI partition and see if this solves your problem. The commands are given below.

sudo disktuil mount disk0s1
mv /Volumes/EFI/EFI/BOOT /Volumes/EFI/EFI/NOBOOT
diskutil unmount disk0s1


If this does not solve your problem, then undo the above commands and try then other EFI partition. The commands are given below.

sudo disktuil mount disk0s1
mv /Volumes/EFI/EFI/NOBOOT /Volumes/EFI/EFI/BOOT
diskutil unmount disk0s1
sudo disktuil mount disk0s4
mv /Volumes/NO\ NAME/EFI/BOOT /Volumes/NO\ NAME/EFI/NOBOOT
diskutil unmount disk0s4


If this fixed your problem, then you should consider changing the label to something better than EFI Boot. And/or add an icon.