It seems to be a bug:
- ubuntuforums.org/showthread.php?t=2196108&p=13088005#post13088005
- unix.stackexchange.com/a/185979
- bugs.launchpad.net/ubuntu/+source/php7.0/+bug/1793436
- bugs.debian.org/cgi-bin/bugreport.cgi?bug=779842
You most likely symlinked the php.ini between the packages. That’s not supported.
github.com/oerdnj/deb.sury.org/issues/1473#issuecomment-713839096