@Gatej Alexandru Thanks for reaching here! Could you confirm which browser you are using, See this Similar suggestion here-
Updating your application’s Microsoft.Owin.Host.SystemWeb package be at least version and Modify your code to use one of the new cookie manager classes. for example something like the following:
app.UseCookieAuthentication(new CookieAuthenticationOptions
{
AuthenticationType = "Cookies",
CookieManager = new Microsoft.Owin.Host.SystemWeb.SystemWebChunkingCookieManager()
});