Employment Screening Process -Wrong GCSE

I recently accepted an offer for a role at a Big 4 firm that I applied to last year for a Sept 2020 start. The role is to start in Sept 2021. I have accepted the offer, however during. My background check it showed that during my application form I had put B for my English Language GCSE when on my forms it is a C. The reason behind this is that I confused my English Literature grade which was a B with my language gcse. These grades still meet the requirements set forward by the firm for a minimum C in maths and english language.

Whats strange is that they done a background check in summer 2020 and found no other problems. I’ve let my recruiter know and was wondering if this would affect my offer being withdrawn.