I had a look at old articles from the time of the FP4 launch, e.g.
For Fairphone 4, software support is guaranteed until the end of 2025 and includes upgrades to Android 12 and Android 13, but the company aims to extend it even further, until the end of 2027, with upgrades to Android 14 and Android 15 despite support from the chipset supplier expiring. With this unparalleled ambition, Fairphone is aiming to repeat what it succeeded in doing with a previous model: six years of software support from the launch of an Android device.
When they update to A15 directly, I just hope that will happen around the time A13 falls out of support (wouldn’t complain if it was earlier, of course). If that upgrade happens in 2025 I’d be fine with that.