I only know that it is recommended to update BIOS if I get a newer CPU.
You only need to update the BIOS if the new CPU is not supported. If the new CPU is included in the list for your BIOS version, it will be recognised when you install the new CPU. If the BIOS is too old, the computer will not start normallty when you fit the new CPU.
Currently, I have the F12 BIOS update which is from 2021.
That's way behind the current version, which if your mobo is Revision 1.0, is now up to BIOS version F18d, released Sept.2 2024.
Back on Jan.13 2022, Gigabyte issued this note, advising users to update to BIOS version F14:
"Major vulnerabilities updates, customers are strongly encouraged to update to this release at the earliest."
Not only do these BIOS updates "patch" security weaknesses that can be exploited by new viruses, they also fix problems that could cause your CPU to overheat and burn the motherboard, in certain rare circumstances.
https://hwbusters.com/cpu/amd-ryzen-7000-series-burn-issues-our-investigation-based-on-real-data/
Of course your AMD CPU may be unaffected by these overheating problems, but each new AGESA release fixes other instability problems.
I am very scared to do it and I'm unsure what specific update to do
It is true that if things go wrong during a BIOS update, you can "brick" your motherboard and may need to return it to the manufacturer for repair.
If your mains supply is "flaky" and prone to outages, a good (always online) UPS should prevent the computer powering down mid-update. If you don't own a UPS, try to update the BIOS when mains glitches are least frequent (difficult).
Updates
In most instances, you can jump straight from your old BIOS to the latest version. Sometimes you need to update to an intermediate version, before installing the latest version.
When you start a BIOS update, the utility will check your BIOS file and state if you need to run an intermediate update first.
I find the easiest option is to copy the latest BIOS file to a small (8GB or less) blank USB memory stick formatted FAT32 (not exFAT or NTFS). There's a chance the updater might not recognise exFAT and it probably won't detect an NTFS formatted USB memory stick.
Next, I plug the USB memory stick into the rear panel (not front panel), start the PC, enter the BIOS and head over to the BIOS update utility. It should display a list showing all your hard disks, SSDs and the USB memory stick.
Select the BIOS file on the USB memory stick and proceed with the update.
During the update, the computer may restart several times.
Do not press any keys until the update has finished (typically after 2 to 3 minutes). The screen may go blank for several tens of seconds. Do not be alarmed. Be patient.
The new BIOS will probably revert to default settings and you might have to dive in and make a few changes to get back to your normal setup
If your computer attempts to boot from the wrong drive, the update has probably changed your drive boot order (if you have more than one drive).
If you had an XMP memory overclock enabled, the new BIOS may have switched back to the default (slower) JEDEC default speed for your RAM.
If you had a CPU overclock enabled in the old BIOS, the new BIOS may have switched off PBO, etc.
Your carefully crafted fan profiles may have disappeared. Annoying but not the end of the world.
Check also TPM, Secure Boot, etc., if you cannot boot into Windows.
I frequently have to re-enable Virtualization after a BIOS update, to run Hyper-V.
Good luck.