Perhaps this is already known, but I just found out about it today, and I didn't see any other topics about it:

The Jolla Phone, Jolla 1 or whatever you want to call it, will no longer receive new software updates. 3.4.0.24 is therefore the final version of Sailfish OS for the Jolla Phone.

The reasons are basically just that it keeps getting harder to update all of the different software components due to its really old Linux kernel, which is coincidentally also stuck at version 3.4.

Although I completely understand the reasoning behind this decision and would even make the same decision if I were in Jolla's place, it does mean that I'll have to start looking for a replacement for this brilliant little device, which has been serving as my one and only phone for seven years. The paint has chipped off in many places, the battery holds less than 70% of its original charge, five years ago the loudspeaker broke but a month later it magically repaired itself and hasn't malfunctioned since, the SIM card reader is now occasionally starting to lose connection to the SIM card, TOHKBD2 barely works anymore and has turned into an odd fridge decoration, SolarTOH never really worked in the first place though I still attached it every summer, at least 90% of modern Android software is no longer compatible, and it feels like the camera takes grainier pictures by the day. Once, my Jolla Phone was accidentally catapulted across an entire room and came out unscathed. For seven years, I've been able to boast about it still receiving all of the latest updates where other phones are already unsupported before they reach the stores. This monumental embodiment of true innovation kickstarted it all.

So long, Jolla Phone, and thanks for all the fish.

You can read Jolla's official blog about it here: https://blog.jolla.com/jolla7/