If your bios is set to legacy boot, then sda2 is definitely what is getting booted. So even if it were originally a win partition, it now contains a key part of the linux boot sequence, that should be understood.
If your bios is set to efi boot then something important is missing from all the glances at the setup from various points of view, that you have provided, and that missing part might be in sda2
Your partitioning is definitely mbr. Legacy booting is based on mbr and normally used with mbr, while efi booting is based on gpt partitioning and normally used with that. But the boot type can be coerced into the other partitioning type in either direction.
I’m quite confident that sda2 is not what is getting booted and it is an old win bootloader. I suspect it could be deleted without affecting anything.
Maybe I’m wrong. Which is the correct and fastest way to resolve this doubt?
I would mount it and look at its contents and see if there are linux looking contents: grub etc. (in addition to the windows contents that are likely there).
Assuming you have other bootable media, it would be safe to use whatever partitioning tool you like to clear the boot flag on that partition. If I’m right about sda2 and your bios is set to boot in mbr mode, that would stop a cold boot from using any of sda so you would need to run partitioning from a usb boot in order to put the flag back.
but sda5 is the /boot mount partition of Fedora 36… and very probably it is also not involved, otherwise I would have seen the correct f36 entries… Ok, I’ll go into the bios. I wanted to avoid it at all costs. What exactly do you want me to check?
Each bios is different, but usually there is some section controlling boot settings. Usually that has some choice of “legacy” vs. some alternatives. It might be legacy vs. efi and within efi might let you choose “secure” or not.
There is also likely some “boot priority” or “sequence” section in bios settings. For efi, often the contents of that are unreadable codes. But if readable, that would be helpful information.
sda1 & sda2 seem to be relics from windows and probably could be removed with no problems. Using MBR boot the mbr (first 512 bytes on the drive) actually launches the grub boot loader which for fedora 37 seems to be on /dev/sda3 as you said.
Yes, I’m very close to write a “fix” to the os_prober, just for the sake of it, lol. At least to simplify the manual management of the entries, in case I want to keep those two Fedora versions and those two partitions