I updated Create as the new patch (0.5.1f) on Fabric released today. Game will not launch with this addon installed. It seems create changed their creative mode tab implementation and any addon that adds items/blocks to the normal Create tab is broken.

Log:
latest.log

Latest version still results in a crash on fabric 1.20.1

large version changes like that are never likely to be compatible without an update from the addons. I recommend downgrading create again until the addons can get an update out.
Thanks for informing us though we will get an update out asap

Can confirm the same issue with 1.19.2.

This was fixed in 1.2.2 and 1.2.1