Thank you for the additional context!
The ‘pos’ part of the string is referring to the position the product appears in based on the search criteria.
For example: When you search ‘peanut butter’, three products appear. The first one will display pos 1 in the string since it was displayed first, the second one will display pos 2 in the string since it is displayed second, so on and so forth.
This is expected behaviour across all stores and I do not believe there is a way to remove this from the URL. May I ask why you wish to remove it from the URL? Is this negatively impacting your store somehow? Please let me know!
Thanks so much,
Elle