SERVER-116329 renamed the FLE2 query types prefixPreview -> prefix and suffixPreview -> suffix. For backward compatibility during mixed-version upgrades, the old values are still accepted (mapped to the new types) but blocked at collection creation time.

                                                                                                                                                       Once 9.0 is lastLTS, the following deprecated artifacts can be removed:                             

  1. IDL enum values — SuffixPreviewDeprecated ("suffixPreview") and PrefixPreviewDeprecated ("prefixPreview") in src/mongo/crypto/encryption_fields.idl (lines 62-67).                   

  2. Collection creation blocks — The uassert checks that reject suffixPreview/prefixPreview at creation time in src/mongo/db/shard_role/ddl/create_command.cpp (line 215+).

  3. Backward-compat mapping — Any helper code that translates the deprecated values to the new names (in query type helpers from commit 5772996cbd2).