If some part of your system or your infrastructure decides at runtime where a particular instance of a building block gets executed, then the deploment view should at least explain this behavior.
It might be useful to create a “dynamic deployment concept” in arc42 section 8 and refer to this concept from the deployment view.
If you doubt such a dynamic mapping: Some modern architecture styles (like microservices, self-contained systems or especially serverless-architectures) already said bye-bye to static mapping of building blocks to specific nodes…
See also:
- Eberhard Wolff: Microservices-Book
- Self-contained systems
- Martin Fowler on serverless architecture, and an impressive implementation based upon AWS-Lambda.