I don't have an iPhone, but can't you just remove all replacements from System Preferences?
If that doesn't work or if you want to keep the replacements, try to uncheck Edit > Substitutions > Text Replacement, or run a command like this:
for d in $(defaults domains|tr -d ,);do osascript -e "app id \"$d\""&>/dev/null&&defaults write $d TextReplacement -bool false;done