Which KiCad version needs updating - Install or Docker image?

[CoreProduction]

I've been using kikit successfully with KiCad5 and a docker image. Now I'm attempting to use the latest KiCad 5.99 with kikit:nightly
Upon trying to run kikit to panelise a design made in KiCad 5.99, I get the below error and I'm a little confused - does this mean I need to update the version of KiCad installed on my machine, or does it imply the version of KiCad used in the docker image is obsolete?

An error occurred: KiCad was unable to open this file, as it was created with
a more recent version than the one you are running.
To open it, you'll need  to upgrade KiCad to a more recent version.

Date of KiCad version required (or newer): 07/22/21

[yaqwsx]

KiKit does not support KiCAD 6 at the moment (there are missing parts of the API - see #85). Therefore, you cannot use KiKit for your KiCAD 6 designs. Docker image is prebuilt with KiCAD 5. This is why you see this error message. KiCAD cannot open never file formats.

[CoreProduction]

Thanks for getting back to me so quickly, Jan - I must have misinterpreted some posts. It's a real shame to hear that the upstream bottleneck is holding up such a great project. Appreciate your work