Looks like all fares below V after 3/31 are being cleared out right now. Example flight on 4/22:
AS 1350SEA 04/22/21 11:25 AMSFO 04/22/21 1:35 PM73J Daily 95% / 18mJ7 C0 D0 I0 U0 E0 Y7 B7 H7 K7 M7 L7 V7 S0 N0 Q0 O0 G0 X0 T0
I'm wondering what's the new fare code for F upgrades since U is taken for the F award.