yankee4210 you are correct on that. But mixing switching power with outlet breakers is not a good idea even if it is legal because if the outlet trips a breaker there goes your lights also. It is better to have dedicated breakers for lighting/switching and it makes it much easier to use green energy to power those dedicated switching breakers for free with the advancement in LED lighting

i'm getting some conflicting answers on this

The reason you are getting conflicting answers is because a long, long time ago this was allowed.

Nowadays, you can't do it. The circuit breaker must match the smallest wire on the circuit. So 14 gauge wire cannot be put on a 20 amp breaker.

As yankee said, you could switch out the breaker for a 15 amp one but the better alternative is to just use 12 gauge wire. It isn't that much more expensive.

There are also certain receptacles that are not only required to be on 20A circuits they are forbidden to provide power to non-receptacle outlets like lights.

Assuming the situation Ron cites above doesn't apply, you can add your light to the 20 amp circuit if you use AWG 12 wire for your light wiring

IMO it's unworkmanlike and just plain bad practice to mix wire gauges on a circuit, even if you change the breaker to protect the smallest wire used.

You can not if you keep the 20 AMP breaker. If you replace the breaker with a 15 amp, someone in the future might see 20 gauge wire connected to it and assume they can replace the 15 with a 20. Do it right and use 12 gauge wire.