Dig one up and look at the roots. My wild guess would be that the compost has issues and would not pass the cress test.

The plants remind me of those we have on places where we had a manure pile laying for a long time. Compacted, weird nutrient situation and probably soil that couldn’t breath for a year. We usually get no crop there but a lot of broadleaf weed, more specific Chenopodium album. After one season the weeds supposedly did there job and “fixed” the soil.