As a result I installed the "Control Panel for Youtube" chrome plugin and Im able to fix it back to 6 videos per row. I also found I could make shorts play in the traditional youtube player by default - which is an added relief.
this is the story of the big company web sites
- huge budget
- best programmers
- terrible design
- terrible usability
- doesnt make sense
- gets worse over time
it's unreal. seen on many major sites.