From your error message, The project will find the favicon.ico in the path of ...\wwwroot\wwwroot\favicon.ico , But your favicon.ico just under the wwwroot folder, So you need to change your code like:
<link rel="icon" type="image/x-icon" href="/favicon.ico">
href will default find file under wwwroot folder, you don't need to add wwwroot in the path manually.
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Best regards,
Xinran Shen