We have a Magento2 site, which has Product and Category URL Suffix as / not .html
But in our catalog_product_flat_1 table, the url_path still contains .html which doesn't seem to cause any issues, as the products still load with / at the end.
But for categories, an issue occurs when a category is saved. It changes the URL from / to be .html ending. So in the catalog_category_flat_store_1 table.
If we do a find and replace in the db table for .html to / it saves fine, but then immediately reverts back to the .html ending.
The only issue seems to be on saving of a category, which causes a chain of wrong URLs.
Any ideas on how to start resolving? Happy to provide more information if required.