Portrait mode on stage light mono and high key mono is clicking colored pictures and not black and white pictures

I recently bought an iphone 12 pro max, and started facing some camera issues. 2 days back I discovered an issue with the portrait mode. Portrait mode on stage light mono and high key mono is clicking colored pictures and not black and white pictures. This issue wasn't there earlier since it used to click black and white pictures only, but somehow now its clicking colored pictures. Need assistance.