I also have this problem with my main TSB account so we’re not alone, when I fill up at the shell garage near me it comes up as a completely different name and throws my categories out of place . At least with monzo you can change it which is great! I’m not sure if it’s down to Monzo or the card machine system?
A little off topic but like to share experiences - I know somebody who flies all over the world selling petrol pump contracts, he knows about oil refinery to a very high level. As a car kinda guy I only ever use Shell V-Power in my S3 and since talking to him I was right to do so, he advised to avoid all supermarket fuels whenever possible as the quality is that poor, regardless of RON value, it’s about the additional minerals being added that is important for your motor, diesels especially!