I’ve just seen someone ask for a Lyft code on the Lines app. A Liner replied with her own code. Both will probably get $5 credit. These credits are one-off for new members only. After that, you’ll never get one again.
There are much better offers available than this. I made this mistake when I found an Uber code like the one described above for my first trip. This year I was smarter and got a $50 code for Lyft.
Don’t ask people online for codes or use codes individuals have posted. (They’re doing it for their own benefit, not yours.)
Google “Uber / Lyft new rider promo code” and you’ll find much better deals.