Observed behavior
Moving INatsSerialize to a new assembly caused ABI break in 2.7.0:
https://github.com/nats-io/nats.net/commits/872fb9578366cf835e5f355e1e6214244ebc6aaf/src/NATS.Client.Abstractions/INatsSerialize.cs
So any methods with serialize/deserialze as params are going to break when referenced in packages built targeting pre-2.7.0 NATS.Net
Potential Fix
Short of moving them back, it may be possible to use TypeForwardedToAttribute
Server and client version
Client: 2.7.0