My hard drive is full and it causes the system to freeze periodically (mouse pointer is working but nothing is clickable, shortcuts also don’t take effect). I deleted some space on my Windows partition to give it to Fedora, but between the two there is that 512 MiB partition identified by “bls_boot” flag.
You should not be performing this task with the OS running since expanding p5 would have to be done on a live file system. Certainly not wise on the root file system.
Boot to a live usb, install gparted, then make the changes (move p4 and expand p5).
After the changes are complete reboot to the main installed OS. That should work cleanly and cause no issues.
First unmount /boot/efi and then after that umount /boot. These two are special in that they need not to be mounted while the system is running. They only need to be mounted when doing system upgrade.