This may be obvious to many of you and this is a purely technical note, but for a URL to be somewhat unique, generally you need to have at least one character after the trailing slash followed by the question mark. So if you have a URL that ends with /? it is the same thing as that being just /.
Generally, what follows a /? are additional parameters that make the page load something dynamic from a database. If the URL just has a ?, then it has no additional filters or details from what the main / URL contains.
Of course, you can code anything, so technically, you can make it have unique content on the /? page if you want, but generally that is not how sites work.
That is why John Mueller said on Twitter “Using just “/?” at the end of a URL is equivalent to not having anything after the slash. You need at least 1 character after the “?”.”
This was specific to a feature in Search Console, here is the context:
Using just “/?” at the end of a URL is equivalent to not having anything after the slash. You need at least 1 character after the “?”.
— ⛰ johnmu is not a cat ⛰ (@JohnMu) October 11, 2022
Anyway, this is something to keep in mind when reviewing sites and in general, it is something good to just know.
Forum discussion at Twitter.
Note: This was pre-written and scheduled to be posted today, I am currently offline for Simchat Torah.