Since HA Core 2025.2.0 update, MQTT empty payloads don't work anymore

Since HA Core 2025.2.0 update, MQTT empty payloads don't work anymore: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). EDIT: As @JosephRDawson found out, this seems more a problem of empty payloads, see below. Changing title.