What is the reason for the the differing spellings of similar words in the Holy Quran, such as "إنما" (innama) and "إن ما" (in ma), or "إما" (imma) and "إن ما" (in ma)?

The current orthography of the Qur'anic manuscripts (masaḥif) is an adherence to the Uthmanic masaḥif that were written by the Companions. Many imams have explicitly stated the obligation of following them. The variation in the orthography of some words within them traces back to how they were written in the original masaḥif. Scholars have mentioned several reasons for the variation in the orthography of some words from one place to another in the Uthmanic masaḥif, some of which are clear and some that involve a degree of forced interpretation. It was said that whatever its reason is not apparent falls under the category of permissible variation in writing, and that the conventions of writing and orthography during the time of the Companions allowed for such variation. Among those who adopted this approach is Ibn al-Banna in his book, Unwan al-Dalil fi Marsum Khatt al-Tanzil (The Title of the Proof in the Written Form of the Revelation). He mentioned reasons for the variation in the orthography of words, such as connecting "innama" and separating it according to the meaning, as well as separating "wa in ma nuriyannaka" in Surah Ar-Ra'd and connecting "fa-imma nuriyannaka" in Yunus, justifying this by the presence or absence of the answer.