“Never criticise the pope” has never been a Catholic rule. Ever.
There has also never been a rule that says, “Only saints can criticise popes”. Nor has there ever been any rule that says you can’t criticise a pope on the internet or other public forums.
All that stuff is in fact made up. And pretty recently. Mostly since we started feeling, in the early 1980s, with more and more bishops going weird and wiggy on us, that the pope was the last bastion of sanity in a world gone pazzo. But the history of the Church is longer than the last 40 years.