Question about old Pro plugin version

A new client has an outdated version of the Pro plugin, v1.3.1, and I’m wondering if some odd behavior that we’re seeing is related. We’re going to be switching to a pure Shopify site in less than a month, so I’d prefer to avoid buying a new license for the latest version if possible, just hoping to isolate the problem and whether it’s even related to the plugin.

Basically, the default permalinks to product post types on the WP site are changing at seemly random times from /products/[product-name] to /collections/[product-name], which gives a 404 page error. The slide-in side cart component also stops working. Trying to load the /products/[product-name] URL manually redirects to the collections version.

I haven’t been able to reproduce conditions on a cloned site to make this happen. I’ve tried doing a manual product sync, and updating various posts and pages (in case some event is triggered by those actions), and I’ve looked in the .htaccess file after it happens for any redirects added there.

Does this sound familiar, could it be caused by the mismatch of the old plugin version with the latest WP core version?

Any ideas would be greatly appreciated.

Thanks,
David