Right-wing (as well as non-woke) news sources commonly run stories about liberal hypocrisy because it resonates strongly with that audience. Because of this, certain segments of the Western world are well aware of hypocritical liberals who break mask or lockdown rules: Nancy Pelosi, CNN reporter Kaitlan Collins, BLM protestors, etc. etc. Conservatives view mask shaming as partisan because woke media outlets limit their attacks to their ideological enemies. So, some conservatives believe that mask mandates are a liberal ploy designed to shame and control conservatives. Some conservatives push back by not wearing a mask.
I would point out that many conservatives and Trump supporters are not anti-maskers. If you watch footage of a Trump rally on Youtube, you will see that many in the audience do wear masks.
There is also a segment of the Western world that believes in a globalist conspiracy. According to that worldview, globalists would love to use mask mandates, lockdowns, and mandatory vaccination as a way of controlling the population.