The memes are cute, but I think a distinction has to be made between people who
A) Disagree with or doubt something, but do not let it affect their daily behavior (or it’s not something pertaining to their behavior in the first place), keep studying the issue or else if it’s not really affecting them set it aside, generally support the Pope and do not complain or badmouth, and
B) Use a subject of their doubt or disagreement as the basis for justifying themselves committing sins and/or rejecting or badmouthing the Pope or the church.
Plenty of people have doubts or find something hard to accept. Sometimes they discuss it with their priest or other Catholics and come to some conclusion on it for themselves, mentally, but it is not affecting their daily activities, nor are they using it as a basis to be negative towards the Church, so it’s hard to see any sin occurring. Doubt in and of itself is not a sin.