What is the meaning of "there is no doubt after completing the ghusl," and does this apply to doubting whether water reached a part of the ear after ghusl?

The obligation in performing a thorough ablution (isbagh) is based on the strong presumption that water has covered the entire body. This is sufficient, and certainty is not a condition. If, during the ghusl, you doubt whether you have washed a limb, then wash it. If you have a strong presumption that water has reached it, then the requirement has been met. However, after completing the ghusl, do not pay attention to any doubt regarding washing a limb, as doubt after completing an act of worship is disregarded. If you become certain that you did not wash a specific spot (e.g., if it is dry or you remember with certainty), then you must wash only that spot without repeating the entire ghusl, because continuity (muwalat) is not a condition for ghusl according to the majority of scholars.