Steps to reproduce the issue

In the administration area, go to the site modules and order the modules using the custom order. Then try to drag an item at the end of the template position it belongs to. You will see that it isn't allowed.
Notice: you need to have modules in the list from other template positions except the one you are interested to.

Expected result

When using the custom order of the modules, it should allow you to put an item at the end of the group of the modules that belong to the same template position.

Actual result

Currently it allows you to put the module in all places among the modules of the same template position except the last one.
(When you filter the module list to show only the modules of the specific template position, then there is no problem.)

System information (as much as possible)

Joomla 4.1.5

Additional comments

Please see the video to understand easier the problem:
https://demo.impression-estudio.gr/_issue-tracker/module-cant-be-placed-last.mp4