Ticking sound

Hi All,
This morning our Prius 2 from 2005 (400k km) developed a sort of car cough. It is a repeating ticking sound which originates in the cabin, it is not noticeable from outside, nor with hood open. It continues while the car is activated. It is there when stationary without the motor running.

It seems as if a something plastic is trying to move something else in a mechanical way, maybe a lever operated by a motor, but fails to and repeats and repeats.
The sound is kind of familiar, I am quite sure I have heard it before, but i think its is then combined with a whirring noise and the ticks is only a couple of times. Could be that this normally happens only after the car is shut down, but I am not sure about that.

Any suggestions what this could be? I would think something with the climate control system, but it is still there also with airco off.
In this thread relays or the brake pressure pump are mentioned: Curious Sound: is this normal?. But what when it does not stop but goes on and on? And how to further diagnose and fix?
Seems similar to this: ticking sound - new | PriusChat

I cannot upload audio/video files, here is a pixelfed-link to the video and links to a locally hosted audio file and same sound with video:
Prius 2 diagnostic issue - Pixelfed
audio: m4v,177KB: Nextcloud audiofile
video: mp4, 3.5MB: Nextcloud videofile
Thanks,
Ben

HTML:

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