It looks like this was raised and then closed on the repo, but I can’t really tell what the conclusion was. It seems like itch needs a change on its end.
itch.io does have a setting (that should be changed by the uploader) to enable the appropriate headers. It’s not enabled by default as it breaks some existing games when enabled.
Calinou | 2022-10-25 15:44
Ah you’re right, I found the thread saying they’re offering a project setting to enable them. Developer Updates - itch.io
ghoulbroth | 2022-10-25 20:35
Hm enabling the option removes the error message for Chrome, but all nodes seem to be invisible. I made a test project with UI elements and my mouse cursor changed correctly, even when I couldn’t see the nodes.