Hello!

1.20.3 introduces a change to the NBTCompressedStreamTools#a(...) method adding a new parameter.
You have to provide NBTReadLimiter.a() as second parameter to call this method.

Info:
https://mappings.cephx.dev/1.20.3/net/minecraft/nbt/NbtIo.html
https://mappings.cephx.dev/1.20.3/net/minecraft/nbt/NbtAccounter.html

My Mojang mapped code:

NbtIo.readCompressed(inputStream, NbtAccounter.unlimitedHeap());

Did you test with 2.12.2? That's already in the release(also targeting 1.20.4, as 1.20.3 is dead).

Nope I will do a test but the new signature of this method is still there on 1.20.4
https://mappings.cephx.dev/1.20.4/net/minecraft/nbt/NbtIo.html

Anyway I see you already added that signature compatibility, so it will surely work fine!

I mean, all tests are passing in 1.20.4, including reading files/streams. So its all already implemented in the latest release :D