It seems that latest OTA update (3.1.2 for Fairphone 6) does contain some critical malfunctions on the Fairphone 6: Feedback for v3.1.1 - #122 by Gaea
I would recommend to wait until a fix will be found, before to install /e/OS on the device.
(I also have a brand new FP6 waiting for /e/OS to be installed)