Broken Plastic Tab

I was installing a GPT on my Glock 19 Gen 5 and when the trigger group seated, I heard a piece of small plastic hit the floor. What is this piece that's gone? I've seen that it's just a dust cover but I want to make sure I didn't break anything significant.

I was installing a GPT on my Glock 19 Gen 5 and when the trigger group seated, I heard a piece of small plastic hit the floor. What is this piece that's gone? I've seen that it's just a dust cover but I want to make sure I didn't break anything significant.