Yeah, man!!
The Gigabyte Software is a real
CRAP.
Like @Bobins said you're not alone... I'm in the same situation too.
My motherboard is a Z390 Designare.
My App Center is the same as yours: B20.0504.1
If you go to the support site for your motherboard (at least in my case) all the software is very old.
If you go to the utility's support page you won't find the versions app center is suggesting.
A TOTAL MESS !!
So you better run the last mile and go to station-drivers (for my motherboard the site is:
https://www.station-drivers.com/index.php?option=com_content&view=article&id=2310:z390-designare&catid=255&Itemid=169&lang=fr).
The site is in french but without much effort you can use it (my tongue language is spanish).
But be warned:
1. You're on your own so better make backups because you manually have to do everything and if you don't exercise caution you can make things worse.
2. You won't find there Gigabyte software.
So,
Good look.
J.