Comment by grapheneos

It's inaccurate information. Qualcomm is willing to provide 8 years of support from SoC platform launch. Android also fully supports using a newer userspace on top of an outdated device support platform. Treble provided a very good implementation of it.

Fairphone chose to use T2Mobile as their ODM designing and making their devices. They chose to use the SoC platforms they did. They chose to focus very little on providing updates to the point that the Fairphone 5 and earlier have an end-of-life Linux kernel without security support. Fairphone 5 is still presented as supported with many years to come but it's not getting a large portion of the high importance security patches anymore.