Hi @longskott1 
! Welcome to the forum.
You can choose to downgrade pacman to make it work with pamac. To check the available versions in your cache, use ls -ltr /var/cache/pacman/pkg/ | grep pacman. After that, you can install one of the older versions like sudo pacman -U /var/cache/pacman/pkg/<old-pacman-package-name> where <old-pacman-package-name> is the package you chose from the previous command.
@Rafael has already compiled a newer version of yay, so update your system with sudo pacman -S yay or sudo pacman -Syu yay to fix yay.
If you want to use the latest version of pacman instead, you can still use it on the command line until the developers of pamac catch up with the updated release.
Thanks for being a part of the RebornOS community. Please don’t hesitate to contact on any of the platforms (Discord, Forums, Facebook, or Twitter) if you need help with anything.
Have a nice day!