It is gparted or parted that makes the efi or ESP partition look like it has a boot flag. That is only because users know boot flag is for booting.
It really is a gpt partition code that defines efi partition. Some UEFI systems have efi boot files in another recovery/data partition and may somehow move boot flag to convert data partition and boot into recovery.
And in actuality it is a long GUID code that defines partitions.In GPT fdisk, ESPs have a type code of EF00. In libparted-based tools, you mark the ESP as such by setting its "boot flag." Note that the libparted "boot flag" means something entirely different under MBR, and you should not set the "boot flag" on any OS partition under GPT!
Pastebin does not seem to be working. May be due to pending upgrade to forum.