ZP999 touchscreen suddenly has a dotted line on the bottom

Hi,

A couple of days ago there was suddenly a dotted little 'line' to see on the bottom of the touchscreen. (see photo)
It is 'inside' the touchscreen and not on the screenprotector to be precise.
Anyone know how that may come ?
Perhaps a false screen-cable-connection inside due to a sudden shock by misplacing the phone too hard on a surface ...?

Any possible solutions without replacing my screen would be welcome !

Thanks for the help !

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