The IFO lost lock just before maintenance started while the SUS_CHARGE guardian was in the state SWAP_BACK_ETMX. The lock loss happened at 14:58:35 UTC, between the last two lines below from the Guardian log.

2024-05-21_14:58:22.768728Z SUS_CHARGE [SWAP_BACK_ETMX.enter]
2024-05-21_14:58:22.768728Z SUS_CHARGE [SWAP_BACK_ETMX.main] ezca: H1:SUS-ITMX_L3_DRIVEALIGN_L2L_GAIN => 0
2024-05-21_14:58:22.769665Z SUS_CHARGE [SWAP_BACK_ETMX.main] ezca: H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN => 184.65
2024-05-21_14:58:42.790151Z SUS_CHARGE [SWAP_BACK_ETMX.main] ezca: H1:SUS-ITMX_L3_ISCINF_L_SW1S => 4

ETMX seems to move too much after the the L2L gain is applied.