For a comprehensive list of other examples of issues with item positions in the Creative inventory, click here.
All tickets associated with item placement in the Creative inventory are valid for cases introduced in 1.16 and later as per this comment. Exceptions exist, which are valid for their own reasons.
The bug
Shroomlights and wart blocks both grow as constituent blocks of huge fungus canopies. Despite this, they aren't grouped very closely at all in the Creative inventory, despite what one may expect.
How to reproduce
Open the Creative inventory
Locate Shroomlight in Decoration Blocks
Locate Nether Wart Block in Building Blocks
Locate Warped Wart Block in Building Blocks
Note that these don't even all share the same tab
Attachments
Comments 11
Relates to MC-1797.
They arnt grouped for everything nether, the shroomlight is for lighting decoration when the other blocks have a different purposes thus the different categorized tabs...
Can confirm, shroomlights are also part of huge fungi, so they may be supposed to be in the same tab as wart blocks.