Cyrillic modifier small a

It marks a pronunciation detail, not an extra letter in a word. Phonetic transcription records how speech sounds; one Russian pronunciation dictionary places the raised a among several versions of a vowel. That dictionary’s symbol guide explains the exact distinction.

Printed use reaches back at least to a Ukrainian phonetics book from 1955; a Russian pronouncing dictionary also includes it in 2018. The wider raised-Cyrillic convention appears in descriptions of Yugur and Evenki too.

Can normalization turn it into plain Cyrillic а?

Yes; compatibility cleanup can flatten the raised form. Unicode maps 𞀰 to full-size Cyrillic а under compatibility normalization. Text processed with NFKC or NFKD, two such Unicode forms, can lose the raised distinction.