Classic Headlight Problem

I was driving my Rangie LSE classic home last night using low beam. I activated the headlight washers and this caused the headlights to turn off. Let the washer arm go and back on comes the lights. Repeatedly. Switching to high beam saw them unaffected.
Can anyone suggest what is happening please?

Cud be the washer fluid getting into the low beam surkit when you squirt it?

...or the relay thingummy that tells the headlight washers squirters that the headlights are on might be duff?