Identifier of a user visible on the url of his image

I created a member list that I display on the front side.

I was wondering if it is not a security problem to see the identifier YptNkRHn of the user appear in the url of an image?

If so, is it possible to change this? And how ?

No, I don’t think so. This identifier is a random string that has no relation to the actual user (at least not outside the app). You cannot use this to log in.

If you want to avoid this string to appear anywhere, you can store the files in another place than the user.