Hi, I edited the category of your post to the issues & assistance category since this is not a user introduction (unless you would like to make it one :D)
I had a search on the forums for your issue, and found a command which should solve your problem (link to original post):
update remote keyring
This will install the archlinux and chaotic keyrings, and then proceed to update your system. 
From this it sounds like you have a partially updated system(?). This command should fix that for you. If you want to be on the cautious side since it sounds like this will also be a really big update, you should make a manual snapshot.
Also, I understand you didn’t see the issues & assistance template since you posted in the wrong category. In the future when you’re seeking help, please make sure to use the right category and include the full output of garuda-inxi, which can also be found in Garuda Assistant under ‘system specs’.
Hope this solved your problem, if not then I hope there will be more experienced users who can chime in. 
Hmm, coming back I noticed something in your post.
Are you using sudo pacman -Syu or something like that to update your system? In Garuda, it’s recommended to use garuda-update -a to update your system, as it will automatically refresh your mirrorlist for you unless you specify --skip-mirrorlist. The -a flag means your AUR packages will also be updated, so you don’t have to do it with Paru yourself.