>21_[ f ]_SEQ1239
Assuming that SEQ is short for sequence then the sequence 1239 can be interpreted as 'auq'
Source: "Conversion list for base 26 Alphabet Numbers and base 10 Decimal Numbers"
https:// www.minus40.info/sky/alphabetcountdec.html
>22_SEQ_FREE_9-ZBA
>22_WH_POTUS_PRESS
>Divert-ATT_CAP_H