These thread states occur on a replica server but are associated with connection threads, not with the I/O or SQL threads.
        In MySQL 8.0.26, incompatible changes were made to
        instrumentation names, including the names of thread stages,
        containing the terms “master”, which is changed to
        “source”, “slave”, which is changed to
        “replica”, and “mts” (for
        “multithreaded slave”), which is changed to
        “mta” (for “multithreaded applier”).
        Monitoring tools that work with these instrumentation names
        might be impacted. If the incompatible changes have an impact
        for you, set the
        terminology_use_previous system
        variable to BEFORE_8_0_26 to make MySQL
        Server use the old versions of the names for the objects
        specified in the previous list. This enables monitoring tools
        that rely on the old names to continue working until they can be
        updated to use the new names.
      
        Set the
        terminology_use_previous system
        variable with session scope to support individual functions, or
        global scope to be a default for all new sessions. When global
        scope is used, the slow query log contains the old versions of
        the names.
From MySQL 8.0.26:
Changing replication sourceThe thread is processing a
CHANGE REPLICATION SOURCE TOstatement (from MySQL 8.0.23) orCHANGE MASTER TOstatement (before MySQL 8.0.23).The thread is processing a
STOP REPLICAstatement.This state occurs after
Creating table from master dump.Reading master dump table dataThis state occurs after
Opening master dump table.Rebuilding the index on master dump tableThis state occurs after
Reading master dump table data.