Two free tools I built for my own audits. Run them on your site, get the headline problems, and get the full report by email.
GA4 audit tool
Enter your site and I check whether GA4 is installed, whether it loads once or twice, whether ecommerce events are present, and whether the consent state is set before the first hit.
Checks whether your tagging server is on a first-party subdomain, whether cookies are set with a long expiry, whether the custom loader is in use, and whether GA4 and Meta requests actually go through it.