Probably not. We’d hear a lot more about it here on the forum if 25.000 phone were defective. Though it may be the case that there is an exceptionally bad batch of batteries, or the design of the phone makes the battery more susceptible to physical shock when the phone is dropped, or the thermal design of the phone isn’t optimal (see for background for example this CNET article on battery and lifetime). There’s a thread on smartphone failure rates in which some information may (or may not) surface soon.
Any battery of the type used in the Fairphone (and most other smartphones) is susceptible to this problem. Unless the failure rate is exceptionally high, I don’t think there will be a mass recall and they’ll stick to warranty exchanges for those users affected. Going onto the forum (and support pages) of any other manufacturer will list a number of threads about swollen batteries, it’s not a unique or new problem. You’d get recalls if it turns out that the battery, on failure, doesn’t swell but for instance explodes or catches fire.
There are at least 10.000 devices out there that have a battery that is nearly 2 years old (and another 50.000 that are anywhere up to two years old), at which point battery performance can be quite degraded depending on how heavily it was used. Rechargeable batteries still suffer from aging effects, and this is normal for the product type. This is why battery warranty is usually shorter than the warranty on the device itself - battery expected lifetime is always shorter than the expected lifetime of the device. So people are starting to replace batteries that haven’t failed, but have started to wear out based on normal wear and tear.
There’s nobody who can lend you a phone for a couple of weeks? Seems a bit drastic and wasteful to throw out a phone just because you’re waiting for a warranty replacement part.