question #3 Sahih Muslim 694c, Book 6, Hadith 23 : What does Ibn ‘Umar’s practice of varying the number of rak’ahs based on whether he prayed alone or with the Imam indicate about following the Imam in prayer?

The Messenger of Allah (ﷺ) said two rak’ahs at Mina, and Abu Bakr after him, and ‘Umar after Abu Bakr, and ‘Uthman at the beginning of his caliphate; then ‘Uthman observed four rak’ahs, and when Ibn ‘Umar prayed with the Imam, he said four rak’ahs, but when he observed prayer alone, he said two rak’ahs.