Marks are not moved when new lines are inserted

I have this behaviour in the plugin for Qt creator.
When I place a mark using the m mapping, and then add lines of text above the mark, moving back to the mark using ' brings the cursor that many lines above the spot where the mark was placed.
Although not a major issue, this is not the behavior of the vim editor.

No file or test is named. Start by locating the FakeVim mark implementation and the handling of inserted lines, then reproduce the issue by placing a mark, inserting lines above it, and jumping back with '. Done means the mark follows its original text position, matching Vim behavior.

Written by the indexing model from the issue text.