New features

In case of error, KiKit tries to build the panel and places error annotation into a board with the suffix .failed.kicad_pcb. In that way, the user can easily spot where and which error happens (d1bbcdf)
The GUI used to be pretty limited in features it supports, e.g., you couldn't set page size due to limitations in KiCAD API. This wasn't very clear for many users. The user must now specify an output file in the GUI where the panel is saved. The PcbNew window is just used for the panel preview (8aca5bf).
There are new parameters you can customize for V-cuts such as text position, size, etc. (a0c1e44, 2e25a3d)

Bug fixes

the KiKit library symbols have now proper attributes (599be77)
layer selection in GUI was fixed on Windows (551e670)
compatibility with KiCAD 8.0.4 on Windows was ensured.
text on bottom layer not being mirrored on Windows was fixed (0de661c)
outdated dependencies were updated (e0c312a, eac56af)
accommodate for some numerical instabilities (69bcf0b, 28409eb, acbd021, a7873c2)
error reporting was improved (3636a3e, 32187ad)

upgrade KiKit backend (see https://yaqwsx.github.io/KiKit/latest/installation/upgrading/)
upgrade the symbols and footprint library via PCM