One of the best pieces of advice I got concerning terrorism was not to be too afraid. If we live in fear, we let the terrorists win. And if we give the government many powers to "fix it", then, as devs like to say, now we have two problems. Remember, what powers you give "your side" to fix a problem can then be abused by the "other side" when they get their turn.
I'm always open to solutions for such terrible problems as mass shootings. But curtailing individual liberty means that the terrorists win. Look at Xinjiang: that is where we are headed in 20 years. The only way to completely prevent terrorism is to lock down every aspect of every life. Hence Xinjiang. The question is simply how slowly our politicians will try to force this upon us.
It is for all these reasons that the idea of "reporting suspicious behavior" bothers me. It is a perfect lever that will inevitably be used to political means or to settle grudges. It enables the use of the police as a club; think "swatting" but worse. Please don't support this sort of nonsense.