Does inserting a wet finger into the anus while cleaning invalidate the fast, given that this is the only way to achieve complete purification due to a health necessity?

The majority of jurists are of the opinion that intentionally inserting a finger into the anus during istinja' (washing after relieving oneself) invalidates the fast, especially if the finger is wet. The Maliki school and Sheikh al-Islam Ibn Taymiyyah hold the view that this act does not invalidate the fast. Sheikh al-Islam further opined that an enema does not break the fast at all because it is not considered eating or drinking. It is safer to adopt the view of the majority; therefore, whoever does this while fasting must make up that day.