I have connect the plugin to github, but I found the user profile image can't load correct.

The image link is https://mattermost-server/api/v4/image?url=https%3A%2F%2Fassets-cdn.github.com%2Fimages%2Fmodules%2Flogos_page%2FGitHub-Mark.png, it return 403 error.
And I found GitHub-Mark.png is 404, can the plugin use my own profile image?
Yes, seems like the image the plugin pointed to (a github hosted image) no longer exists. The proper solution is to include the image with the plugin and have it serve it through the REST API. I'm planning on updating the plugin in the next few days with the fix but if someone wants to work on it instead feel free
FYI there is currently a discussion about how plugins should handle static files: https://community-daily.mattermost.com/core/pl/qm9houtcx7rgtf9akeyci5htqr
I'm going to work on this now
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FYI there is currently a discussion about how plugins should handle static files: https://community-daily.mattermost.com/core/pl/qm9houtcx7rgtf9akeyci5htqr