Stuck for 4 hours in the same queue spot

I've been here for 3-4 hours now, and the queue on the website went from 1640 to 1400 and something in the meantime, why am i not going up in the queue ?
https://imgur.com/a/2cud5PO

Because Premium players take your place (premium = skip queue). If there are 1000 Premium players that connect during your queue, then that lengthens it.

I fully understand that but being stuck on the same position for several hours, is a bit odd in my opinion

If you do understand there's nothing to find odd.
Each donor that logs in means an extra player you have to wait to get in yourself. In fact, your position in queue is increasing each time a donor logs in, but the client doesn't supports showing that, only decreases, so instead your position is shown as staying the same when it might actually be higher and only decreases when enough regular players log out to push it lower that the "hidden" increased value.