why is my facebook ads conversion tracking so messed up and showing weird data?

hi everyone, just launched my saas and trying to get facebook ads running for sign-ups. i'm a total noob with this stuff and honestly, it's been a bit overwhelming.

• The Problem: My conversion tracking data in Facebook Ads Manager looks totally off. i'm seeing super weird numbers, like things just dont match up at all.
• Specific Issues:
  • huge discrepancies between Facebook reported conversions and what google analytics shows for sign-ups. sometimes it's a difference of like 30% or more, makes it really hard to trust the data.
  • sometimes it looks like conversions are missing entirely. like i know people signed up, but facebook just doesn't report it.
  • i'm really not sure if i've set up the facebook pixel and all the custom "sign-up" events correctly. i followed a few guides for basic facebook pixel implementation but maybe i missed something crucial for saas.
• Main Question: What's the best way for a beginner to properly set up and troubleshoot facebook ads conversion tracking for saas sign-ups? is there some kind of checklist or a really foolproof method?
• Seeking: any tips or step-by-step guides would be super helpful. especially if it covers common pitfalls for new saas founders trying to get this right.

really hoping someone can help a new founder out! waiting for an expert reply.