Unfortunately, it’s one of the missing subscripts in unicode — see the table on the Wikipedia page @mauro3 linked. Unicode simply has not defined superscript q or subscripts b, c, d, f, g, q, w, y, z. It’s all very silly.
See GitHub - stevengj/subsuper-proposal: Draft proposal for additional sub/superscript characters in Unicode for a draft proposal to the Unicode standards committee to try to rectify the situation.