When flint and steel is used on (for example) stone along a wall, occasionally mine craft simulates the light from the fire, however 1 tick later the light is corrected causing a flash.
Linked issues
Comments 3
Force updated, still happening.
Duplicate of MC-4923, please use the search function to see if your bug has already been submitted. Currently over 55% of tickets are being closed as duplicate.
Performing force update just to be sure.