Researcher Derik Kauffman discovered that #Apple maintains a hidden, undisclosed multilingual list of approximately 100,000 words and phrases that its iPhone keyboard blocks from autocomplete and swipe-typing suggestions. This list, referred to as a digital "#greylist," does not prevent users from manually typing these terms but makes them difficult to enter via predictive or spoken features.

Some #censored words include slurs, swear words, and references to drugs, sex, and violence (e.g., "fuck," "al-Qaeda," "Auschwitz"), derogatory or critical political slogans such as "dictator Trump," "sleepy Joe," "right wing conspiracy," "Tibetan independence," and "United Ireland."

Different languages have specific blocked terms, such as "Modi braggart" in Hindi, "immigration too high" in French, and "occupied territories" in Hebrew.
https://techcentral.co.za/apple-autocomplete-grey-list-iphone-keyboard/288130/