Can confirm, and is actually not texture pack related.
That's because spectator mode has "no-clip" or, no collision. This is working as intended. Since the border blocks make a border, (which has collision) the spectator clipped through the border, due to spectator having no-clip. (it's intended!)
This is Working as Intended
This happens on Switch WITH a Microsoft Account. (and Xbox 360 Live accounts!)
You see, that's a shrub, it was a Legacy Console exclusive item, and when transfered onto Bedrock, it becomes that exact item. Thus, in conclusion... You had a Shrub
Not resource packs that are the problem. I have the VDX4J resource pack, which only touches the us er interface. The Sniffer did work before. Investigated further, and apparently the textures list completely leaves it absent.