Let go because I was performing at senior (not staff) level, where do I go from here?

When i joined this company I had previously been a senior machine learning engineer/data scientist, with about 5 years of experience. In the time after joined I had manager A who gave me 'expected' ratings for about a year and a half, then switched under manager B. Under this manager, I received a 'moderate' (as opposed to 'expected') rating during my mid year performance for which i was put on an 'action plan' (was told specifically it was NOT a PIP). After successfully finishing the goals on the plan I was moved under manager C. During our 1:1s we talked about potential plans for me as he was in need of regular software engineers to support their ML products and was trying to see where I would fit in. He also expressed surprise at my moderate rating as 'it didn't align with [his] experience' (direct quote). Other than that he had no feedback for me during our 1:1s, even when I specifically asked for it. Imagine my surprise when I logged onto our yearly performance review and HR is in the call to explain that I had received yet another 'moderate' rating and I was being terminated that day. Manager C read off a script and primarily mentioned feedback about projects/work I had done under manager B, not under manager C. After being terminated I initially thought maybe manager B just had it out for me, but I just had a chat this morning with former manager A who confirmed that it was indeed manager C who put in the second rating. Her feedback was that had I come in as senior, I likely would've been fine, but as staff I needed to be more self-directed. I'm struggling to figure out what to do with this information. It's been two weeks since my firing and I'm dealing with lots of feelings of hurt, distrust and fear. But at the same time, I can also honestly see where the feedback may have come from. While I certainly didn't wait around twiddling my thumbs, maybe I just don't have the breadth of knowledge or experience to perform at a staff role? I have no idea. I thought I was on the path of self-directedness. I had created a research reading group for our org, I had developed an internal SDK that was used by a few teams across the company... I'm already scheduling interviews and screenings but I would really like not to experience this ever again, obviously. What can I do to be better? I feel like I usually spend a lot of time catching up on ML news/technologies that maybe I lose the bigger picture and don't know how to build a better product... How/when did you move from senior to staff, how did you become a "force multiplier" (ugh)?