No problem! Thank you for letting me know; I probably wouldn't have realized the issue without your inquiry!

IMPORTANT NOTE 4: I forgot to do a couple steps of the migration to the No-Mirror method and completed them. Everything should be operational (for real this time)!

So it turns out, I missed two crucial steps of the migration to the No-Mirror method. Did those just now and verified that I can download my own patches. Hopefully that means everything is unborked!

Tried that too on my end with the same results. Something's certainly borked, but I'm not sure what.

In addition, I imagine letting others know in the Touhou Patch Center Discord Server could help a bunch! The maintainers of the servers and creators of THPatch are certainly more well-versed at this sort of thing.
discord.gg/touhou-patch...

If you can, can you certify that any other of my patches work correctly using the no-mirror version by trying to download it from a fresh thpatch installation? It would be a great help to deduce the problem.

Thank you very much for reaching out! I'm guessing the migration to have repository no longer use mirrors.thpatch.net could've gone awry. I'll look to see what could be causing the trouble as soon as I can!

IMPORTANT NOTE 2: Replaced instances of the mirrors.thpatch.net server with a No-Mirrored version across my entire repository. Everything should be operational!