I found the answer here
Dependency Injection in Owin
… each time the OwinContext is pulled from the HttpContext, it returns a new context … if we are applying DI terms here, then your object is registered in per-request scope, as you would expect to be DbContext.
And I recently learned the difference between “transient”, “scoped” and “singleton” in this answer.
It turns out a page request of our (very large) project (in development mode, where caching of static files is off) causes 125 requests to server, which caused the issue.
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