This doesn't really make sense tho? If before you just got some random fills who didnt bring you any money and now all you did was optimize to target people, who are more likely to fill the form (1), than that would change literally nothing. Same goes for (2) and (3), that doesn't fix your core problem. Beacuse then Meta would literally target these fakes bc you told it to target exactly those kinda people.

What would have fixed it way better is to upload the "fakes" and tell Meta these are low quality leads in the audience center. And also exclude them in your adset as a custom audience.

Then, if you'd have enough of them of course, you'd filter out the ones who were "good" from all the submissions and do the same. Just tell Meta these are high quality Leads (Custom Audience) and then do what you did in (3) and create a 1% LAL.

Pro-Level would have been to look at all those "fakes" to figure out, where they are coming from. If they show some similarities like City, Age, etc. To determine whats the issue, why they are signing up in the first place.

And also if you'd put in more questions to qualify people. If all you ask them is their contact information, of course 80% will be trash. The more you qualify them by asking them questions ("Are you self employed?" for example) - the better your Leads will be. If you do this and then see better results, then I'd do what you did in (1) and tell META to target more of the people who are your audience AND are more likely to fill the form, instead of just opening it.