All that I can find in PubMed (search string "Kratom neuropathy") is a fairly technical mouse model paper which suggests that compounds based on the main active ingredient in Kratom may be effective in treatment of neuropathic pain.

There is nothing there which implies that ingredients of Kratom can cause neuropathy.

Orally active opioid μ/δ dual agonist MGM-16, a derivative of the indole alkaloid mitragynine, exhibits potent antiallodynic effect on neuropathic ... - PubMed - NCBI