Strange temperature readings from Heated Bed

Hi there,
I have always had this strange temp chart from my bed, see screenshots. It doesn't seem to cause any problems, I just wish to understand why it reads like this... I have double and triple check the connection, and it seems like everything is Ok there.
I am on FW 1.12 still, but it was like this all the time, so to say. Is it something I could eliminate or reduce with the new FW tune features?
Thanks!

I think you have either a bad thermistor connection, or the bed thermistor is picking up interference, perhaps because there is a short between the thermistor connection and the bed plate or something else.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].