How will my lack of subject tests impact my admission chances for UCs?

I did… and I saw it before as well. I just was wondering about this part:

submission of these test scores (just like submission of AP and/or IB scores) may add positively to the review of your application." >

I was wondering how much of a drawback it would be if I didn’t add one compared to a student who does. Like, would that be a huge deciding factor or would it not matter at all. Sorry, i don’t mean to waste your time.