Not 100% sure here - but it may be removed from the AUR because it is now in the main repos. I see that community hosts both iscan and iscan-data now. Presumably you can remove the Aur version, and do a normal pacman -S iscan iscan-data. (not sure you would even need to remove the AUR version, it might get replaced by the repo one)
I was able to solve this problem earlier today as follows:
I first completely uninstalled iscan and iscan-data:
$ yay -Rsn iscan iscan-data
I then reinstalled iscan and iscan-data:
$ yay -S iscan iscan-data
yay tells you that iscan-for-epson-v500-photo and its dependencies will be installed instead of the requested packages:
:: Checking for conflicts...
:: Checking for inner conflicts...
[Repo:2] libjpeg6-turbo-1.5.3-2 libpng12-1.2.59-2
[Aur Make:1] deb2targz-0.1-7
After installation completed, I found that iscan appears again in my application menu, iscan launches normally, and my Epson Perfection 1240U scanner works as before.
To confirm that iscan-for-epson-v500-photo has provided iscan, run this command:
$ yay -Qi iscan
Name : iscan-for-epson-v500-photo
Version : 2.30.4-3
Description : iscan (from Epson) with the plugin for scanner Epson V500 Photo, also called
GT-X770 - iscan[community] is out-of-date and buggy
Architecture : x86_64
URL : https://support.epson.net/linux/en/iscan.php?model=gt-x770&version=2.30.4
Licenses : custom:EPSON
Groups : None
Provides : iscan iscan-data iscan-plugin-epson-v500-photo
Depends On : libjpeg6 libpng12
Optional Deps : None
Required By : None
Optional For : None
Conflicts With : iscan iscan-data iscan-plugin-epson-v500-photo
Yes, the new AUR version points out in its description that the community version was buggy:
I was having problems with the version of iscan (184.108.40.206) that was removed from the community repo. Most frustrating, it was impossible to select a rectangular area of the preview image for final scanning. I’m pleased that this problem has been resolved in the new version (2.30.4), and I haven’t experienced any other problems, so far.