GA4 and Conversion Tracking Expert Needed

I have a med spa client using Boulevard for booking. There is an issue with GA4 attribution and Google Ads conversion tracking. A conversion will show in Google Ads, but on GA4 is attributed to organic, and a lot of purchases aren't being attributed back to PPC in GA4. We have the ads set to take visitors to a landing page where they can either call or book. I have the conversion event set up through Google Tag Manager with conversion trackers to all of the different domains that visitors can land on. The GCLID is supposed to be passed through, but it doesn't attribute to some purchases while it does on others. I'm trying to build a case study out of this client. Without the proper attribution, I can't see what's actually going on and be able to show the results that I'm actually delivering. My ideal hire is an expert in GA4 with experience in third-party booking tools and attributing those all back to Google Ads. I would like for you to fix it or tell me how to fix it, and then teach me what was done and where it went wrong. I have a decent understanding of GA4 and conversion tracking, but I wouldn't say I am an expert. Overall, it's just messy, and I would really like clarity/clean attribution. I would love to jump on a call and go over things.