First of all, recalibrate your Joy-Con from the console settings (System Settings > Controllers and Sensors > Calibrate Control Sticks) because sometimes it's just software and fixes itself in a couple of seconds. If that doesn't work, cleaning the joystick contacts with a little isopropyl alcohol sometimes helps temporarily, but honestly it's like putting a band-aid on a bigger wound.
The thing is, Switch Joy-Cons have a reputation for failing pretty quickly, especially the left one. It's not like you're the only one; lots of people complain about the same thing after a couple of years. Nintendo has actually offered free repairs in some cases, so it might be worth reaching out to them or checking if your console is still under warranty. If not, getting it fixed at a service center usually doesn't cost too much, but depending on where you are it could end up being almost the same as buying new controllers.
Buying new Joy-Cons is more expensive in the short term, but they last pretty long if you take care of them. If you play a lot and the left one keeps giving you problems after cleaning, I'd say invest in new ones instead of dealing with something that doesn't work properly. In the end, you'll be using them for years more and there's nothing worse than stick drift in a game like Zelda.