uefi – How can I expand the /boot/efi partition on Ubuntu 20.04?

The file system of this NVMe SSD uses is called MBR, or Master Boot Record. This means it can have only 4 primary partitions. One of the primary partition can be a “special” primary partition called extended partition. In your case this partition is /dev/nvme0n1p2. See the list in the bottom half of the picture in your question.

Extended partitions can have many more partitions inside it. These partitions are called logical partitions. The Ubuntu system partition with the mountpoint / also shown as /dev/nvme0n1p2 is a logical partition.

You have shrunk the logical partition /dev/nvme0n1p5. By doing this you have created 1 GB unallocated space inside the extended partition /dev/nvme0n1p2. You can only use this space inside the extended partition to create more logical partitions. You don’t want that.

Boot the compute from Live USB in the Try Ubuntu mode. In the picture above right click on the /dev/nvme0n1p2, the extended partition and select Resize/Move. Then shrink the partition to match the /dev/nvme0n1p5.

Now you will have unallocated space in between /dev/nvme0n1p1 and /dev/nvme0n1p2.

Now you will be able to expand the /boot/efi partition /dev/nvme0n1p1.

Don’t forget to click Apply after each step.

Hope this helps