How accurate is the fb pixel at tracking conversions

I have been running a few fb ads and having some good success my issue is that the fb pixel is not tracking all of my conversions so it's hard to how my ads are truly preforming. For example today I did 5 sales (Shopify) but the fb pixel has only tracked three of them. On my pixel it is not showing any errors. Any suggestions?

One of mines, I’m doing a Purchase campaign right now and my stats are so far off. I even purchased the WooCommerce Conversion extension and it’s still off. It’s crazy.

Unfortunately that happens, and the reason lies in FB - it's glitching sometimes.
The good news is that it fixes itself in time, you just need to wait a bit.

FB Pixel is not good at tracking conversion because many people(including myself) use script in order to pixel think like buyer make a purchase, but that's not true at all.

And the reason behind people run script in their console is they wanna see more ads like that.

Last point is pixel don't really know it is an actual human being which buy product or just a script that run in console.