Problematic tests list (33 rows):
bugs.core_0733_test  Compress Data over the Network
bugs.core_2264_test  ALTER DOMAIN with dependencies may leave a transaction handle in inconsistent state causing segmentation faults
bugs.core_2966_test  Wrong results or unexpected errors while sorting a large data set
bugs.gh_7436_test  Backup error for wide table
bugs.gh_8488_test  MIN/MAX aggregates may badly affect the join order in queries with mixed INNER/LEFT joins
bugs.gh_8926_test  Indexes may not be used for multiple ORed conditions containing both field and non-field references
bugs.gh_8965_test  Wrong PERCENT_RANK computation
functional.arno.optimizer.test_opt_sort_by_index_10  ORDER BY ASC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_13  ORDER BY ASC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_19  ORDER BY ASC using index (multi) and WHERE clause
functional.metacache.core_4386_metacache_test  Error 'object in use' must NOT raise in 6.x with shared metacache (opposite outcome to prior versions).
functional.replication.test_blob_access_when_no_grant_for_select  Replicator must have access to the table with blob regardless SELECT grant on this table to the user who created blob.
functional.replication.test_blob_characters_garbled_when_conn_charset_differs  Characters are garbled when replicating fields with type BLOB SUB_TYPE TEXT if the character set of the connection and the field are different
functional.replication.test_blob_not_found_in_rw_replica_if_target_row_exists  Error "BLOB is not found" while replication converts INSERT into UPDATE for a conflicting record
functional.replication.test_blob_segments_longer_32kb_are_not_replicated  Problem with replication of BLOB segments longer than 32KB
functional.replication.test_dblevel_triggers_must_not_fire_on_replica  Replica DB must not fire DB-level triggers but their activity on master must be eventually seen in replica
functional.replication.test_ddl_triggers_must_not_fire_on_replica  DDL-triggers must fire only on master DB
functional.replication.test_disallow_rdb_backup_history_replication  Disallow replication of RDB$BACKUP_HISTORY
functional.replication.test_duplicated_segment_numbers  Replicator could produce log segments with duplicated segment numbers
functional.replication.test_duplicates_in_rw_replica_after_conflicting_insert  Conflicting INSERT propagated into a read-write replica may cause duplicate records to appear
functional.replication.test_failed_ddl_commands_can_be_replicated  Failed DDL commands can be replicated
functional.replication.test_generator_could_not_be_transferred_to_replica  Generator values may not replicate after commit
functional.replication.test_grantor_not_changes_in_replica_if_owner_not_sysdba  DDL-Changes in replication does not set the correct grantor
functional.replication.test_invalid_msg_if_target_db_has_no_replica_flag  Invalid message in replication.log (and possibly crash in the case of synchronous replication) when the target DB has no its "replica" flag set
functional.replication.test_lookup_problems_for_intl_data_in_unique_indices  Lookup problems for INTL strings in unique indices
functional.replication.test_make_async_reinit_reliable  Make asynchronous replica re-initialization reliable #8324
functional.replication.test_missed_privilege_for_object_belonging_to_non_dba  Replication stops if GRANT issued by NON-DBA user who has RDB$ADMIN role and appropriate object (table, etc) belongs to another user
functional.replication.test_oltp_emul_ddl  Applying full DDL from OLTP-EMUL test on master with further check replica
functional.replication.test_permission_error_on_ddl_issued_by_non_sysdba  Permission error with replication
functional.replication.test_shutdown_during_applying_segments_leads_to_crash  Crash or hang while shutting down the replica database if segments are being applied
functional.replication.test_some_updates_crash_server_on_replica_side  Some updates can crash Firebird server on replica side
functional.replication.test_sync_replica_server_hangs_on_disconnect  Synchronous replication hangs on disconnect [CORE6497]
functional.replication.test_updating_blob_with_empty_string_stops_replication  Replication gets stuck due to "Blob xxx.xx is not found for table xxx" error

This list is the same for:
4.0.7.3251 2026.02.24 4fb4ad2c  CS