I'm growing my peppers in the polytunnel this year - first time - as well as outside and they've been fine and strong but I noticed two in the tunnel were looking odd and smaller than the rest so I got them out. Now another is starting to look the same - photo below. I don't know what it is and there are no pests on them and I've checked the soil beneath the two I took out and there was nothing there either. Good root system on both. The peppers outside are slightly smaller but are fine.
Coincidentally, in another part of the garden, well away from the polytunnel, a patch of margarites which I grew from seed are showing the same symptoms. There is a patch of about 25 or so and over the course of a week almost all are starting to look like the photo below. Margarites planted in other parts of the garden and from the same pack of seeds are fine.
Here are the pepper leaves
and here are the Margarite leaves
I don't mind if the Margarites have to come up but I would hate to lose all the pepper plants as we eat a lot and they are so easy to freeze and store.