It does feel good. But no. They had no notable defects. They just wilted and died
Yeah I would seriously consider what minty said. Again what's the type of plants you are potting?
It may be cheaper and less of a headache to dump everything the pot and start with fresh potting soil the next time.
And again sometimes you just get a bad batch of plants from the Homeless Despot/bLowes. It happens. Save the receipt, you can return them for replacements or a refund up to a year. If that's the case buy new ones of the same kind and return the dead ones in the pots. But don't be a retard about it and try to stuff a 8 year old dead tree into a sapling starter pot.
You have cats, and they may be peeing on the plants or other animals may be also. The added height lends to increasing the perimeter of the scent. I have one particular jasmine that was struggling because my beagle boys would all compete for that same bush, and it really suffered until the root system expanded enough to balance all that urea. Now it's the Terminator jasmine bush, the stalks are almost covered in bark, very vibrant plant, constantly blossoms, and sufferers very little from the couple of freezing months I have here. If that's the case you may need to just rinse off the leaves. Because animal urine dries into this residue and that can block the breathing pores on the underside of the leaves.
You may have grubs in that soil, so right after the plant dies, dump out the pot and see if you have any grubs living in the pot. Grubs tend to be whitish in color. Think really gross caterpillars.