Polar flutter affecting K7EK WSPR signal

Attached is a screen picture, showing K7EK signal received in my QTH on 40m.
It is not obvious on the WSPR screen, but on spectrum lab it was difficult to recognize a WSPR signal, as it was completly frequency spread out.
Of course no Decode...
Strongly suspect the effects of polar-flutter...

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Image icon k7ek.png94.16 KB