1. The number of times after a leader election a node goes into member state ROLLBACK. The server also logs some other metrics related to replication rollback like how many operations are being rolled back: https://github.com/mongodb/mongo/blob/fb679bde06827e98f7c55272a83c754959a3ffd6/src/mongo/db/repl/rollback_impl.cpp#L1529
2. The number of times a chunk successfully migrates. https://github.com/mongodb/mongo/blob/fb679bde06827e98f7c55272a83c754959a3ffd6/src/mongo/db/s/migration_source_manager.cpp#L634-L635
3. The number of times a node has 0 read tickets or write tickets available for operations. This kind of metric probably requires post-processing the contents of the diagnostic.data/ directory. It is something we can defer until exploring more into deadlock scenarios. https://jira.mongodb.org/browse/SERVER-75205 is the type of bug I'm thinking of to know "would it be possible for Antithesis to hit this?"