Banding issue

[Burly]

I took some data of m52 the other night now i didn't get a lot of data ,dithered images every 3 rd image ,flats and bias ,stacked in Siril using no Darks Script now im getting some banding, screen shot from processing
after Wipoe to show issue ,do you think this issue being caused by my Flats ? if not what is possible other cause ,i take flats with an EL panel,

[admin]

Hmmm... that's a pretty atypical pattern indeed!

Might it be something as simple as faint cirrus clouds or dew?

[Burly]

Thanks Ivo , the conditions were not the best to be fair so high cloud is a possibility( I did have dew heater on) , I will see how next outing goes .