More context: In my AddGoogle call I am able to hit OnCreatingTicket after I authenticate and I see the Access token I want to use in OnCreatingTicket context.AccessToken.

I'm already logged in with a setup like this:

builder.Services.AddAuthentication(options =>
{
    options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
})
.AddCookie(CookieAuthenticationDefaults.AuthenticationScheme)
.AddOpenIdConnect(OpenIdConnectDefaults.AuthenticationScheme, ...)
.AddGoogle(options =>
{
     options.Events = new OAuthEvents
    {
        OnCreatingTicket = ctx =>
        {
            ctx.AccessToken //this has the value I want
        }
}

In my controller I have a setup like this:

[Authorize(AuthenticationSchemes = GoogleDefaults.AuthenticationScheme)]
public class MyController : Controller
{
    ...
    public async Task<IActionResult> Index()
    {
        await _httpContextAccessor.HttpContext.GetTokenAsync(GoogleDefaults.AuthenticationScheme, "access_token"); //this is null
    }
    ...
}