Netherite Upgrade not renameable in resource pack

I've tried to rename the Netherite Upgrade in a resource pack, among other items. All of the other items had their names properly updated, but the the netherite upgrade stayed the same. I've taken the translation key straight from the 1.21.4 jar file, and even double checked on the wiki, but it doesn't seem to be updating with it.

The line in the en_us.json file:
"upgrade.minecraft.netherite_upgrade": "Testing name"
(No comma at the end becasuse it's the final line, before '}')