Were the abrogated verses written on the Preserved Tablet, or does the Preserved Tablet only contain the Quran that is currently in our hands? And was Ubayy's Mushaf a recited Quran, even though he continued to worship with it even after the death of the Prophet, peace and blessings be upon him?

The entire Holy Quran is written in the Preserved Tablet (Al-Lawh Al-Mahfuz), including the abrogating (nasikh) and abrogated (mansukh) verses, as indicated by Allah's saying: "Nay, but it is a glorious Quran, in a Preserved Tablet." (Al-Buruj: 21-22). Ibn Abbas and others interpreted Allah's saying, "Allah erases what He wills and establishes [what He wills], and with Him is the Mother of the Book" (Ar-Ra'd: 39), to include both the abrogating and abrogated verses, and all of that is in the Mother of the Book. As for the individual Mushafs of the Companions, such as the Mushaf of Ubayy ibn Ka'b, they did not conform to the Imam Mushaf (the standard Mushaf) upon which the Ummah agreed. They might have included unusual readings (qira'at shadhdhah), solitary narrations (ahadiyyat), or interpretations, and the Ummah did not adopt them for recitation. The claim that Surahs Al-Khal' and Al-Hafd are part of the Quran is not accepted, and Ubayy's writing of them in his Mushaf does not prove their Quranic nature, for the Quran is only established by continuous transmission (tawatur).