Why was "ri'a" in Surat An-Nisa not written as "riya"?

The Companions wrote the Mushaf without distinguishing between the two words in terms of their form. As for writing "ri'a" with a hamza, it is not appropriate to ask why it was not written without a hamza, for the word, in the recitation of the majority of reciters, is with a hamza, and there is no reason to write it without a hamza. Whereas Abu Ja'far recited it by substituting the hamza with a yaa', so it is written in his recitation as "riya" without a hamza.