A shared mutex contention in VSS lookup becomes visible after MCOL-5472 is resolved.
Version Substitution Structure is a structure that gives PrimProc the actual version of a block if there is any DML operation in progress. Any block scan operations looks for a block using blocks' LBID before it reads the block from a persistent storage. VSS is node significant.
The suggested solution is to horizontally scale VSS cache having multiple caches. hash(LBID) mod number_of_caches can be used to deterministically pick a cache from the list.