FWIW, I’ve had much better success with pepper plants in pots than in our (dubious) ground. It may be the roots are particularly needful of good drainage? They (pepper plant roots) always seem “fragile” to me, too, and then slow to recover. But... in this case the plants must have germinated from seeds stuck together. So, I did the best I could with the strongest plant, and “we’ll see” about the weaker ones, I guess. The other option would have been to just chop the weaker ones @ “ground level”, but then there’s even more dead root material intertwined with the best plant’s roots. I don’t know if that’s problematic or not, but, it seems like a recipe for disease and rot.
Pepper plants do better for me in “partial sun” than full sun, too.
However, I’m beginnning to wonder if a problem with potted plants is that the soil / potting mix in the pots gets too hot on sunny summer days here. I’ve already started shading spots in the ground and pots of tomato plants not shaded by the plant itself. It seems to help.
I have seen several you tube videos recently that say that, yes, while tomatoes and peppers are WARM weather crops, they are not HOT weather crops.
The recommendation now is during the hottest part of summer, to use shade cloth.
I’m learning a bunch about container gardening and am more comfortable with trying it next year because I have done OK some summers with peppers, never a great crop. We just don’t have the growing season length for them.