I honestly think the combat would go a massively long way with just 3 key changes - in-depth reaction system - shoving focusing on prone rather than home run yeets - advantage/disadvantage removed from height and backstab
I need to spend more time with the system to really have an opinion, but so far it sounds fair. There are spells that can have enemies flying... I don't think it needs to be available to EVERY character, at no cost and bonus action. My guess is, that they want you and enemies in constant shuffle and fight for higher positions.... but so far it kinda seem to mostly overshadow other considerations.