Don't really know what is wrong, just that they do look very bad. Whatever you are doing is not working well. They do look sickly, or maybe stressed sitting in wet soil.

I would get rid of the soil and get new potting soil. Clean out the pots. Make sure the pots drain well and the soil dries out.

Might consider overwatering. Peppers do not like soggy soil. Also, overwatering flushes nutrients out of the soil, especially nitrates. You should let the surface dry out before watering. Underwatering leads to green droopy leaves. Overwatering leads to curling and yellowing leaves. To the extent we're not looking at disease, there is nothing wrong with your soil.

Thanks both!! I have a feeling over watering could be the culprit like you suggest. Very much appreciated !!

IMPE, when pepper plants look like that, there's no coming back. It might possibly be a virus. Insects can transmit viruses when they feed.

I gave up growing peppers some years ago because thrips began regularly destroying them.