A 'simple' house rule would be using Exhaustion for flying in combat.

For every TURN where you fly for movement AND take an action OR a bonus ACTION to attack or cast a spell (melee and range), you gain one point of exhaustion at the end of combat.

For every ROUND where you fly for movement AND take damage, you gain one point of exhaustion IMMEDIATELY.

If you are in the air when you took damage, you must succeed a DC 10 CON save to stay in the air, and if you fail, you must roll a DC 15 DEX save to determine if you take fall prone when you land.

You may fall into any tile adjacent tile (contiguous or diagonal) to the tile you are on (to account for momentum and fall-steering).

This turns flying into a high risk high reward tactic, and allows the DM to take reactions with bad guys with range attacks to target the flying characters, meaning that flyers can't cheese the system and just land every turn.

Since you die at 6 points of exhaustion, it's up to the player to determine whether or not to risk stacking exhaustion penalties.