Need help : PIP fears!

Hey folks, I need help! I joined a fast paced startup kind of company, last cycle, my performance was not up to the mark, and I was just catching up. Somehow I got things in place. This cycle is found smooth, no major complaints from the manager or anyone (compared to the last cycle) but I suddenly got a HR ping, HR & N+1 was present and they informed me that I will be put on PIP as I am not in sync with the pace of the team/slow in deliverables. Actually deadlines are collectively discussed in sprint planning and I never had any sprint overflow. But my N+1 was saying he can't see that "vibe" in me, that 'acceleration' isn't there where he can commit me to a bigger project. They said they will devise a plan for 4 Weeks PIP and give regular goals for it. Still now my manager didn't say a word to me. I don't know what's happening around here - not a star performer but deliverables are going thru , the manager never reacted or hinted but this news broke on my head! I am worried now, will I lose my job? Is it a way to remove people? Or how to handle PIP? Plz suggest something fishes. Thanks