Will Chinese nationals get arrested if they criticize Xi Jinping in our country?

If a Chinese national or a Joseonjok (ethnic Korean from China) says something about Xi Jinping in our country, will the Chinese public security bureau find out and arrest them?
When identifying Chinese nationals, they often ask them to try criticizing Xi Jinping, don't they?
I am curious if that method is actually effective.
I wonder if they refrain from criticizing him out of genuine patriotism for China, or if they simply cannot do it because they are afraid of being blacklisted by the Chinese Communist Party.