Wikipedia (https://zh.wikipedia.org/wiki/佛系) says:
佛系是中文網路新生的流行語,約在2018年左右開始比較頻繁的在中文網路跟媒體出現,在中文的語境裡大致意思是指怎麼都行、看淡一切、無欲無求的一種生活態度。[1]該詞據考證來源於2014年日本的《non-no》[2],提出所謂的「佛男子」(日语:仏男子)的概念,是指专注于自己的兴趣或工作,不愿花时间与异性交往的男子。[3]
Google Translation:
Buddhism is a buzzword for Chinese Internet new students. It appeared more frequently in Chinese Internet and media around 2018. In the Chinese context, it roughly means anything that can do anything, look down on everything, and have no desires. Attitude to life. [1] The term is based on research from Japan’s "non-no" [2] in 2014. It puts forward the concept of the so-called "Buddha Man" (Japanese: 仏男), which means to focus on one's own interests or work, and not willing to Men who spend time with the opposite sex. [3]
How would you translate 佛系 into English?