It wasnt banned. Theybdidnt meet the advertisment requirments. Its false outrage to generate clicks. Its quite disappointing of them.
It isn’t the first time that the advertising requirements were used to chill speech. It doesn’t matter whether there was a ban; what matters is whether speech was effectively prevented. “There is no God. Now stop worrying and enjoy your life.”
Atheist Bus Campaign - Wikipedia

Wouldnt surprise me that it was. Its what its liekly designed to do. Doesnt mean mullvad werent aware of it and took advantage.