Wanted to start off saying I also sent this same thing to the square-enix support website as well as in-game support which directed me to that website. I've also posted about this on reddit, but thought I'd make an official post on the forums about this issue.
What I've told them about my issue is that ever since DT released I've had this odd extra deadzone on my ps5 controller even with stick sensitivity in the controller settings (in game) set to 0. I do play on PC using the official launcher, not through steam, I just use a controller since I initially started on ps4 a few years ago and have all the muscle memory on the controller so I stayed using that. I did not get this issue prior to DT, nor do I have this problem with other controllers such as the ps4 and xbox series controllers. I've gone back to using a ps4 controller due to this and would much prefer to use a ps5 controller for all it's features.
More information on what exactly is happening is my controller seems to have this odd innate value to the deadzone, which is the amount of force moving the analog sticks for them to actually register in game. In game there is a slider for this is in the gamepad settings in system config and is labeled "stick sensitivity", which for one that's not what stick sensitivity is, this should just say stick deadzone, sensitivity would be how much the camera for example moves when moving the sticks. But anyways, with the deadzone slider set to 0 the controller still takes a noticeable amount of force to actually register in game. This same setting on other controllers listed results in barely any force needed, character and camera will even move on their own if there is slight stick drift. I'm wanting to know why this is happening only on the ps5 controller.
Some things I've done are updating the firmware for the controller, even buying a brand new one and updating firmware. Running it through steam as a non-steam game and adjusting the deadzone that way, which doesn't seem to have any effect as ffxiv seems to override it.
Like I said it's not happening on the ps4 and xbox series controllers I have, and it didn't happen on the ps5 controller prior to DT release. So perhaps something happened with the release with a bug on the controller.
The post I made on reddit about it one person responded saying they've noticed this too. That was about a week ago and it hasn't gotten any other comments on it.
Steps in order to replicate this issue:
1. Run ffxiv from the official launcher
2. Plug in a ps5 controller to the pc and switch to controller mode in game.
3. Navigate to system configuration then gamepad settings and set the "stick sensitivity" slider to 0.
4. Move the sticks around slowly to notice any deadzone.
5. Plug in a ps4 and xbox series controller and repeat steps 3 and 4, noticing the deadzone is much less if any at all, true 0.
Thanks for your time and I hope this issue can be resolved.