What could be the reason for duplicate slug (url) in wordpress?

Question

WordPress

Hello. I have a website with wordpress, wpml and woocommerce installed. 4000 items. Many with the same name.
Recently a strange bug appeared - wordpress stopped appending slug -2, -3 ... -n to the end if the label is already taken. It turns out different products have the same link.
(Such a problem for both post and custom post type).
Have you encountered this? What could be the reason, where to dig?
For the third day I've been fighting, I could neither find nor invent anything.

Answer 1

It turned out that everything is very banal. It was decided by disabling all plugins and connecting in turn. Found a conflicting plugin and updated it.