An authorization hold should happen for all rides, but it's normally not very large. The whole point of it is so you can't get a ride and then have their charge fail because you don't actually have any money. Any company that provides a service before payment can be expected to do the same thing (e.g. basically any company that's part of the gig economy). The perfect authorization hold is one that's for the exact amount you'll be paying later, but in most cases that amount can't be predicted, so companies try to slightly overshoot (because they can always charge less than the hold, but if they try and charge more it will fail if you don't have any more money).

If you got a $25 authorization hold from Lyft there's a couple possibilities that come to mind. The first is that Lyft thought your ride would in fact come somewhere close to $25 (after tip). The second is that if you're a new customer, they likely consider you a much higher risk of fraud, and therefore want to err generously on the side of overshooting the estimate, instead of trying to place a lower hold and risk not being able to capture the real cost of the ride. Also, if you hailed your ride without providing a destination, they wouldn't have been able to produce a usable estimate.