The bug

When typing /datapack list, you can hover over all the data packs you have enabled.
This is like most things in the game, like advancements, entities, and killing weapons, all of which you can hover over to see the object in question.

However, there is one difference between data packs, and these other objects. These objects use their own "actions" in tellraw. You can see this by using the "show_item" action in this command:

/tellraw @a {"text":"Hover","hoverEvent":{"action":"show_item","value":"{id:\"minecraft:stone\",Count:1b,tag:{display:{Lore:[\"Lore line 1\",\"Lore line 2\"]}}}"}}

However, data packs do not do this, which is inconsistent with all other forms of hover events.

How to reproduce

1. Install the attached data pack into world/datapacks/...
2. Type /datapack list
3. Hover over the data pack. ("file/tellraw_bug")
4. See the description reads "This is a description."
5. Go into the data pack's file, and change that description in pack.mcmeta
6. Run /reload
7. Go back into the game, and repeat step 3.
   → Observe that the data pack text has not updated, as the text is generated when you use /datapack