client crash when hard gradient

[800020h]

minecraft 1.20.1
fabric loader 0.15.10
Fabric API 0.92.1+1.20.1
Placeholder API 2.1.3+1.20.1
Colorful Anvils 1.2.0+1.20x
several other mods

attempting to use <hgr:...> in an anvil crashes the client
crash-2024-05-08_23.41.13-client.txt

https://placeholders.pb4.eu/user/text-format/#gradients