Looks like drop in LED headlight bulbs instead of halogen ones are now considered an MOT failure...
MOT inspection manual: motorcycles - 4. Lamps, reflectors and electrical equipment - Guidance - GOV.UK
Headlamp, position lamps, stop lamps, direction indicators, rear registration plate lamp, rear reflector and direction indicator ‘tell-tale’ rules and inspection for motorcycle MOT tests.
www.gov.uk