Hello aspirant

hope you are doing well and safe. As per your query , I would glad to inform you that  their can be any geniuine reason to change your rank into general may be you have to proof yourself sc candidate or your documents was expired . I would advise you to ask for the reason ,then only anything will happen . Their are rare chances to get the category change after admission but yes you can try and hope for the best

Hope you found this answer informative. Best wishes for your future