double message on long push

I noticed that a long physical button push (more than a second or two) results in 2 MQTT messages.

Soon after pressing the button it emits a message with an input_event/0 blank event code, i.e. {"event": "", "event_cnt...

and on button release it emits a message with input_event/0 event code "L" code as expected, i.e. {"event": "L", "event_cnt...

That's totally fine for me but was a behaviour I hadn't expect from the docs.

FYI the button1 is on "fw_ver":"20210323-105237/v1.10.1-gf276b51"