pacman -Qo /usr/lib/mysql/plugin/
/usr/lib/mysql/plugin/ is owned by libperconaserverclient 5.7.19_17-1
/usr/lib/mysql/plugin/ is owned by percona-server 5.7.19_17-1
I was finally able to perform the upgrade by issuing pacman -Syu however I believe this conflict should be properly resolved by package update. I'm not sure what is the proper way to report so I am writing this topic here
Thx!