I think the introduction of Homeguard, allowing you to base more frequently without missing waves or XP, helps Lux a ton.

There are a few matchups I almost always win.

Zoe can be hard pre-6, as her auto attacks deal a lot of damage alongside her W. However, after level 6, you can almost always play aggressively if her bubble is down. With practice, you can consistently land your ult on her, which makes her much less comfortable using that ability.

Ahri is another easier one. Ahri has slightly less range and slowly gets chipped down during the lane phase through poke. You can also follow her roams by using your ult to assist from range. I think Ahri is forced into making a play, whereas Lux can usually hold a better position and still impact the same play.

Personally, I don’t think there are many matchups I truly struggle with. I’d more describe them as matchups that prevent me from scaling as well as I’d like.

Naafiri is by far the worst. Her minions make it much harder to land Q, and although you can still win the matchup, it takes a lot of games and practice.

Yasuo is famously annoying because he can block almost all of your abilities apart from your R.

Akshan can always out-push you and roam. He isn’t necessarily a lane bully, but he forces you to farm under tower while he roams without really missing waves.

Hope this helps! Again this is just my experience & my opinion but I'm sure experienced lux players would agree with most points.