1. What datapack(s) do you have installed (including ones made by me- include version if possible)?
   Datapack Utilities v2.3.0pre1
2. Run /reload. Copy/paste or post a screenshot of what appears in chat (should say [Loaded ]).

Error: Datapack Utils v2.3.0 requires Minecraft 1.17. Click [here] to go to the DU download page for alternate releases.

3. What environment are you running the datapack? (Vanilla single player, Vanilla multiplayer, Forge, fabric, spigot, bukkit, paper, optifine, realms, etc). Please specify exact Minecraft version as well.
   Vanilla single player 21w20a.
4. What if happening vs. what you expect to happen?
   Datapack gives the above message, likely due to line 10 in du:load_message. The datapack still functions correctly.

Yeah, I was testing a new error message format and forgot to disable the test. Getting the message actually means it's working.

It'll be fixed next prerelease.

Of course, thanks for confirming the issue.