Sometimes I see people saying it should be a Bonus Action to cast it but in my mind that makes it too powerful to be a cantrip for everyone who's any decent at attacks (your stereotypical wizard would be less broken with that because they mostly suck at non-spell combat anyway
).
Not necessarily the best reason to do it anyway, but currently you can trivially get Advantage by either walking to a higher spot or behind a target for no Action or Bonus Action, or by using a Bonus Action to Jump into a similar position.
I think given how many ways to get Advantage there are already, making True Strike a Bonus Action wouldn't make combat any worse. Either that or make it apply to all attacks against that enemy for 1 round, or leave it as it is but eliminate the Concentration requirement.
