Users can mount a drive using sshfs, but can't unmount it because of missing permissions

Ubuntu Version:
22.04 LTS Server

Problem Description:
On a server that I have inherited, in a manner of speaking, users can mount drives over the network using sshfs, but trying to unmount them using fusermount -u fails with “permission denied.” I would expect users to be able to unmount drives without root access when they were able to mount them without root access, and would like help in achieving that.

Relevant System Information:
The server has had a number of steps taken to harden it, and it could be that one of those is interfering with the use of fusermount, but I don’t know where to start looking for relevant specifics.

What I’ve Tried:
I tried killing the sshfs process on my test mount, but that results in more problems, for example ls will print out ls: cannot access 'mountpoint': Transport endpoint is not connected and shows the permissions and ownership of the mount directory as question marks.