It's not actually just a warning -

[JijaProGamer]

If I Run

openupm add [email protected]

(Also tried 3.2.1, since 3.0.3 your library wants doesn't actually exist)

and then

openupm add com.lachee.discordrpc

I get this warning:

error CS1566: Error reading resource 'DiscordRPC.xml' -- 'Could not find a part of the path 'C:\Users\bloxx\FitZen VR\Packages\com.lachee.discordrpc\Runtime\DiscordRPC.xml'.'

Which won't allow me to actually run the build

[TornadoOfSoup]

I think this may be due to a missing .meta file for DiscordRPC.xml. I noticed that DiscordRPC.xml exists in the folder when viewed in File Explorer, but doesn't have a .meta file. Every other file with a .meta file in that directory appears properly in the editor, and when I tried renaming or copying DiscordRPC.xml, Unity gave this warning:

Asset Packages/com.lachee.discordrpc/Runtime/DiscordRPC.xml has no meta file, but it's in an immutable folder. The asset will be ignored.

Maybe since it's in an immutable folder when imported as a package, it's unable to generate the .meta file? In this case, it might work fine in development, since I imagine it would be in a normal mutable folder rather than in the package folder Unity doesn't want to touch.

[xflipperkast]

same issue here

[Snow0406]

same issue here