I’m running 3.3.0.beta2, and this component correctly displays the tag sidebar when you first select the tag, but the sidebar is not removed when you select a different tag. You can see this happen with the preview on theme-creator.discourse.org. Here’s how it looks when you visit the art tag:
…but when you switch to (for example) the code tag, the sidebar doesn’t change:
I see that Discourse Category Sidebars has been kept much more up-to-date than this component. I might have a go at applying the same changes to this one.
Update: I see that tag descriptions support HTML these days, so the Tag Banners component is probably better for my purposes. Thanks anyway!