I'm using Manjaro unstable (but stable enough for me) for its better support than Ubuntu or other distros (and I thank the developers for this).
Today I had a notification about a new kernel but fortunately I didn't install it because I discovered that there are no nvidia-340 drivers for kernel 5.8: if I did I would have lost the proprietary drivers plus a lot of time to restore the system as before!
There are drivers like linux58-nvidia-440xx, linux58-nvidia-435xx, linux58-nvidia-430xx, linux58-nvidia-418xx, linux58-nvidia-390xx... but not linux58-nvidia-340xx, and this happens every new x.y release!
I know my graphic card is quite old, but I ask developers to compile nvidia-340xx drivers when they release the other drivers as there are lots of users (you may search in the forum) with old graphic cards like mine.
Hope to see a driver soon.
Thanks and have a nice day.
Stay with Linux 5.4 - for as long as it lasts.
Please do not write meaningless answers if you are not aware of the topic.
I'm currently using kernel 5.7.12 and Nvidia 340.108 driver in a stable way... as they are still OFFICIALLY supported in Manjaro!
I'm just asking developers to release 340.108 drivers the same moment they release the other drivers...
The driver is EOL within a predicable future and this fact has been provided by @steanne by link to the relevant topic.
So X 1.20 and kernel 5.4 is your best bet.
Further comments is pointless.
We will drop 340 drivers from our distro soon, for real. Nvidia is not patching those series anymore. Also our friend who supports us with patches for Nvidia drivers decided not to go thru the hoops anymore. So if Canonical is not updating 340 drivers for Ubuntu, then it is gone for good ...