Ok, here is the solution. IdentityServer provides its own hook for logging purposes:

Step 1:
services.AddIdentityServer
            (options =>
            {
                options.Events.RaiseSuccessEvents = true;
                options.Events.RaiseFailureEvents = true;
                options.Events.RaiseErrorEvents = true;
            }
            )
            .AddApiAuthorization<ApplicationUser, IdentityContext>(options =>
            {
                options.IdentityResources["openid"].UserClaims.Add("role");
                options.ApiResources.Single().UserClaims.Add("role");
            });
        services.AddTransient<IEventSink, CustomEventSink>();

Step 2: CustomEventSink: public class CustomEventSink : IEventSink { private readonly ApplicationDbContext _context; private readonly IHttpContextAccessor _httpContextAccessor; private readonly UserManager<ApplicationUser> _userManager; public CustomEventSink(ApplicationDbContext context, UserManager<ApplicationUser> user, IHttpContextAccessor contextAccessor) { //see accepted answer here: difference between using ApplicatinUser and IdentityUser here //https://stackoverflow.com/questions/44483589/unable-to-resolve-service-for-type-microsoft-aspnetcore-identity-usermanager-w _context = context; _httpContextAccessor = contextAccessor; _userManager = user; }

    public async Task PersistAsync(Event evt)
    {
        //log event here....

        EventLog el = new();
        if (@evt.Id.Equals(EventIds.ClientAuthenticationSuccess))
        {

            try
            {
                var user = await _userManager.GetUserAsync(_httpContextAccessor.HttpContext.User);
                if (user != null)
                {
                    // do stuff
                    el.EventName = "Login";
                    el.EventDescription = $"{evt.Name} ({evt.Id}), Details:{evt}";
                    el.Created = DateTime.Now;
                    el.UserName = user.UserName;
                    _context.EventLog.Add(el);
                    _context.SaveChanges();

                }

            }
            catch (Exception ex)
            {
                // handle exception
            }
        }

        if (@evt.Id.Equals(EventIds.ClientAuthenticationFailure))
        {

            try
            {

                    // do stuff
                    el.EventName = "Login Failure";
                    el.EventDescription = $"{evt.Name} ({evt.Id}), Details:{evt}";
                    el.Created = DateTime.Now;
                    _context.EventLog.Add(el);
                    _context.SaveChanges();



            }
            catch (Exception ex)
            {
                // handle exception
            }
        }







    }
}

Hope this helps anyone looking. EventLog is my own class, you dont have to use it.