How many Quranic readings are there, and have they exceeded the ten readings? Did the Companions have different mushafs from the current mushaf with an increase or decrease in verses?

The number of recorded and accepted Mutawatir (concurrently transmitted) recitations is ten, and their differences are those of variety, not contradiction. The Companions would memorize and write down whatever was easy for them from the Qur’an, and what they possessed might differ from the Uthmanic Mushaf due to the piecemeal revelation of the Qur’an and the abrogation of some of its verses, or because their individual codices contained abrogated verses or interpretations mixed with the text. Therefore, the individual codices were not relied upon in the compilation of the Qur’an; rather, reliance was placed on what was officially compiled during the time of Abu Bakr, because the transmission of the Qur’an depends on the memorization within hearts and chests.