Why Other Players Can't See Your Cape (And How to Fix It)

This is by design

Capes added by this mod are rendered only on clients that have the mod installed. If a friend on a vanilla client says they cannot see your cape, that is the intended behaviour, not a fault. There is no server-side component that pushes cape data to unmodded players, and no account linking is used.

Checking the obvious things

If a friend *does* have the mod and still cannot see your cape, work through these in order:

• Confirm you actually have a cape equipped in the selection screen rather than the empty option.
• Confirm your friend has the mod loaded on their client for the same instance they are playing.
• Check that neither of you is using a resource pack or shader that overrides player rendering.
• Relog on both sides, since cape data is exchanged when players come into view.

Custom capes specifically

Custom capes are stored locally on your machine. Other mod users will see them only if the cape data is shared through whatever mechanism your setup uses. If custom capes never show for others while built-in designs do, the issue is with how the custom file is being distributed, not with your selection.