Parent name spelling on my (US Citizen) birth certificate

[msgc]

I am a naturalized US Citizen. I am applying for my mother's green card. I have a birth certificate with her name on it. But My mother's name is spelled differently in her passport versus my birth certificate - example - Passport states her name as "SHANTHI" but Birth Certificate states her name as "SANTI". So its a minor spelling difference. How do I address this difference?
She has Aadhar card, Pan card and other documents in the spelling as per Passport.
Has anyone encountered this issue and what type of affadavit can I provide?

Thanks,
Maya.