i cant find a way to make this post that long so
The API Class pages on the devhub are case sensitive
Part | Roblox Creator Documentation will load the Class page for Part
However, https://developer.roblox.com/en-us/api-reference/class/part (or any other pattern of upper and lowercase) will 404.
This affects all API instances, not just part
https://developer.roblox.com/en-us/api-reference/class/instance
https://developer.roblox.com/en-us/api-reference/class/marketplaceService
I believe this is due to how the API’s JSON file is registered, meaning ‘part’ is not found in the JSON file.