The FairPhone 4 had a screen brightness bug that made the phone (mostly) unusable outside in the sun that lasted from Feb 2023 to Oct 2023.
Since the Android 12 update, the FP4 has a cooling feature that reduces the maximum brightness even when the slider is all the way to the right.
This occurs when the phone heats up to ~40 degrees at the CPU, which is not a lot at all.
https://forum.fairphone.com/t/random-screen-dimming-while-brightness-slider-stays-at-100-after-a12-update/93195

They will have to work very hard to make me consider buying my next phone from them.
They do seem to listen to their users and learn from their mistakes though - FP4 was often criticized for the short firmware support offered from Qualcomm. FP5 will have Qualcomm's extended firmware support for its SoC.
https://www.fairphone.com/wp-content/uploads/2023/08/Press_release_Fairphone_5.pdf

The phone is great and things can be replaced easily. My only issue with the phone is it's price. It's quite high compared to phones with similar specs.

Headphone jack?

No headphone jack means fairphone now encourage Bluetooth earbuds and electronic waste.

They're dead to me.

I'm in the market for a phone and love this idea, but 8x digital zoom without optical zoom options in 2024 is a non-starter for me.