Why am I getting “Indicate whether to send a cookie in a cross-site request by specifying its SameSite attribute”?

you are getting this because you are using a resource from another site and that server is attempting to set a “cookie” but, it does not have the SameSite attribute set, which is being reported in newer versions of browsers.

this (may) also be shown if you are trying to access the server page from local computer (xampp), which generally doesn’t has SSL installed;

set the header line in your server page (if in PHP) as below:
header("Set-Cookie: cross-site-cookie=whatever; SameSite=None; Secure");

(remember: this must be solved from the server side.)