Oral pigmentation. Variant dangerous?

So I visited a dermatologist today he said its lichen planus for sure, he asked since its 2 months only then you should start the treatment asap, as the earlier the treatment the better the prognosis... All this started post covaxin dose, and after the 2nd dose it aggravated badly in oral mucosa, i know this is a chronic inflammatory disease but if it happened due to covaxin, is there any chance that it will go away? Or i have to live with this forever? I dont have any itching or burning just inner cheek feels rough and it feels very much dry sometimes... I am just 24 and non smoker, non tobacco and alcoholic, why this happened to me? Will this gonna give me problems later? I am most afraid of cancer, and my OLP is probably a variant called LPpigmentous, is this variant dangerous?