Understanding strange partition on multi-boot SSD

My 512G SSD can be booted in windows10 and linux (Ubuntu 20.04). I need to enlarge the windows partition and I have done so in a live-USB linux session using gParted to reduce the size of the linux partition to free some space, and I created an NTFS partition hoping to join it with the already existing one.

However, it seems something prevents extending the windows partition; I notice a 512 MB FAT32 partition between the existing windows and the free space I prepared. I don't dare to delete it without knowing the consequences. Anybody knows what it is or how I find out?

I need an advice on how to proceed. I add a screenshot of three tools showing my config. The Ubuntu Disks tool and GPartded and also the output from lsblk -f . Thank you.

First, you can't merge partitions. You can only enlarge them to include any following unallocated space.

Second, the unallocated space is inside the extended partition, so cannot be added to the Windows partition that is outside of the extended partition.

You should rather move the unallocated space to outside of the extended partition so it follows the Windows partition. Unallocated space cannot by itself be moved except by moving the partitions around it.

What I suggest:

• Take a total backup of your disk
• Delete the empty NTFS partition you have created so it becomes unallocated space
• Move the ext4 partition up so the unallocated space now follows it at the end of the extended partition
• Reduce the size of the extended partition to the minimum so the unallocated space will now follow it but be outside of it
• Move the entire extended partition down over the unallocated space, to move the unallocated space to follow the Windows partition
• Boot into Windows and resize its partition to include the unallocated space.

As said, any mistake can be destructive, so mind your backup.