I have installed Vivaldi from AUR version 2.7.1628.30 and have since discovered that version 2.8.1664.40-1 is now in AUR. The problem is when trying to use the command pacman -Syu Vivaldi is not downloading and upgrading. I have also tried yaourt -Syu with the same problem.
I thought packages installed from AUR got updated along packages from the normal repositories (databases)?
I've just done a search and discovered that I should have typed yaourt -Syu --aur
It's working now.
AUR packages are upgraded for me on updates with pakku and yay using just -Syu.
Here it says "Version tags may not include hyphens!" and it looks like there is a hyphen, but I guess that isn't the problem then.
https://wiki.archlinux.org/index.php/Arch_package_guidelines#Package_versioning (https://wiki.archlinux.org/index.php/Arch_package_guidelines#Package_versioning)
Thanks for informing me about pakku and yay but having used pamac on Manjaro I think I'll continue to use pacman and yaourt.