Flashing to a new BIOS will erase your current settings and you will have to redo any overclock or changes you did in the old BIOS. Yes you can save a profile to an external drive and reload that, but it’s not advisable to do for different BIOS revisions. Normally one would update their BIOS if the current one has issues or there is new support for extra hardware (like a new CPU you plan on getting). The stated vulnerability updates seem like reason enough to update. Just like always, be careful when updating BIOS. I once managed to brick a Gigabyte board due to a bad flash even with dual BIOS on the board. Weird I know, but apparently both BIOS got screwed despite only flashing one of them.
Gigabyte numbers their BIOS releases with a major firmware versions (Fxx) followed by a lower case letter to signify the revision for that major release. So for F61c you were running the 3rd revision of F61. Once F61d was released (presumably to fix a problem) then Gigabyte pulled F61c from their site as it was superseded.
Anytime you see a release without a lowercase letter it signifies the final release for firmware version before moving on to the next major version (F63 in this case). Presumably this will be the most stable revision. If Gigabyte later finds a major problem in the F62 final release they’ll just pull it from their website.
And you can assume this will be the least stable as it’s the alpha release for firmware 63. Or everything might work perfectly fine for you. YMMV.
I generally avoid installing any firmware version that ends in a lowercase letter unless there is a feature or fix in the changelog that I want.
Edit: Sorry, forgot to answer your question. Yes, it will likely wipe all your OC settings and timings. In my BIOS I have a option to save the BIOS profile to a USB flash drive that can be imported back in afterwards. But as a backup plan I’d take photos of all your custom settings just in case. And my vote is to install F62.
If it’s working and you’re not having any issues don’t update. You’ll never know what might happen. Most likely nothing, but it’s not a given.
If it ain’t broke, don’t fix it
Personally I always reset the BIOS to factory before updating to make sure the system is stable (it is in Windows, but who knows when updating the BIOS). If you don’t it’s gonna erase it anyway after the update. So make sure to save them or take note of them somewhere.