In past times I have entered a few, won some but learned the invaluable lesson that photographic competitions are pointless, don't waste your time and talent...
Subject themes are often vague and open to wide (mis)interpretation; judging schemes are dubious and the judges themselves are variable, subjective and opinionated. You mostly lose the rights to your submitted and thus best images plus winning is on the random, biased whims of the viewing panel.
Winning photos often don't even vaguely meet the original competition brief and often have been so heavily manipulated in post that to call them a photograph is a travesty or have been taken in such a way that flaunts the rules and is flagrant cheating or have been chosen by the judges for blatant political reasons. Finally, nobody is impressed anyway.
So, just don't waste your time and talent. That's all I've got to say about that.