@Brian Moncada do you have any idea why this could be happening or has this ever happened to you?

@Ahmed Ali it solved itself, took a few days but now it's showing me people inside of the audiences

Have you set up enhanced conversions? You can schedule a call with you google rep and they can set it up for you.

maximize conversions then switch to target cpa after 7 days or so

Also, the audience signals that you've given google, there millions of people in that audience, and google basically has different types of audiences within that audience. Think of it like small pockets of audiences groups within your audience signals you've given it. And for some reason google could have placed you in the wrong group of audience hence the drop in quality. But again, don't worry, let it spend and give it time 4-8 weeks and it will figure out who your audience is again. So yeah, that's my take, you must have made a change in account or something because the only other thing I can think of is, the time is up with your ads - which will be unlikely, but have you checked your average imp frequency? If it's more than 2+ times t cold audiences then your ad has fatigued. Or the audience is too small, or you've captured all the conversions that were the best conversions available and now you just have to take what it's giving you. which again is highly unlikely. Be sure to let keep us posted when you've solved this would love to know what the issue is.

@Luke Alderson Really? I don't understand what the issue could be then or what has caused this - i still have a slight feeling it's got to do with adding a new conversion goal, even if it's secondly - maybe it's kinda messed up with your data but again that unlikely. Let me know when you figured it out. Thanks @Uzair Farooqi he might able to give a better insight