better to keep product slug as domain.com/slug/p

[that-coder]

It is better for SEO to create a URL in a format like above. Also, some sites will follow a pattern like, domain/slug/p/id
the slug entry may same for multiple products but id may differ.

[okbel]

Do you have any sources about this that we can read?

[that-coder]

In my personal experience, we got better ranking and more traffic generated through this kind of URL pattern making

For reference see how Flipkart is doing

https://www.flipkart.com/samsung-galaxy-max-gold-32-gb/p/itmevakgf8gmvyte?pid=MOBEV7YDBCAFG3ZH&srno=b_1_2&otracker=browse&lid=LSTMOBEV7YDBCAFG3ZH5FUOXG&iid=4a09db74-d220-409a-9714-cb0b5fc55e1b.MOBEV7YDBCAFG3ZH.SEARCH

At the same time, you won't see these kinds of URLs in Amazon and all other top commerce websites since google won't crawl Amazon URL per day instead they will give direct access to their search data store to crawl URLs, and google rank them prior

[alexbs]

or even like this: domain/slug/p{id}
If the slug changes, it is possible to throw a 301 redirect to a new slug.
No need in long word "product".
Also "product" didn't match case, when if it is a "page of a service" (not a good/product)