Since the tables to divs changes were not introduced until Jenkins 2.264 and you're running Jenkins 2.249.x in the video, I don't think this is related to the table to div changes. I've removed the tables to divs regression label based on the version you're running.
There were known issues (
JENKINS-64136 & JENKINS-64040) in Jenkins weekly 2.258 through 2.263 that caused buttons to appear in the wrong locations. However, that problem was not introduced until 2.258 and you're running 2.249.x. You may want to try Jenkins 2.263.1 to see if the problem is resolved in 2.263.1.
The plugins-git-issue.txt file appears to be something like a list of plugins, but contains extra information. One item of extra information is a reference to the TFS plugin. JENKINS-64241 suggests there are issues with the TFS plugin when saving forms. Have you tried removing the TFS plugin?
I can't duplicate the problem on Jenkins 2.263.1 with git plugin 4.5.0. I also did not see the problem with previous versions of git plugin on Jenkins 2.249.3.