Of top tier/high prestige competition, including both club and international football, which tournament has the fairest refereeing throughout the years? The UCL? World Cup? Euros? One of the top domestic European leagues? Factors include quality of referees and decisions, good VAR usage, least corruption etc.
I find these competitions actually have worse standards than many of the domestic leagues. Especially the World Cup, where they insist on having referees from all over the world, so you end up with corrupt and astonishingly incompetent refs from countries that barely have a professional football system