It’s gutenberg. It is making the interface that you see in your screenvideo completely different and not allowing me to load anything into the widget bar. I tested it before by deactivating it, clearly operator error.
What i did was I de-activate gutenberg, then, created my sidebar for my blog posts. Then, reactivated gutenberg, because that’s my editor. This allows me to now have a sidebar and its actual editable through the appearance<customize menu.