Is my job offer still live Compliance Caseworker 503r?

I applied for the HMRC Compliance Caseworker role (503r) last year and was placed on the reserve list. I was recently offered the role and am currently going through Pre-Employment Checks.

However, the results for the newer Compliance Caseworker campaign (558r), which I applied for before receiving the 503r offer, have just come out. I have been placed on the reserve list for 558r as well.

My question is about how these overlapping lists interact. I know that if I were still on the 503r reserve list, candidates with higher scores from the newer 558r campaign might be offered roles ahead of me. However, since I have already been formally offered the job from the 503r campaign and am actively in the PEC stage, is that offer locked in? Or could someone with a higher score in the 558r campaign displace my current offer?