Help me understand EXPLAIN PLAN of mysql 8

Question

-> Sort row IDs: users.userid  (actual time=24875.751..34999.822 rows=2547647 loops=1)
    -> Table scan on <temporary>  (cost=0.00..0.50 rows=6083517) (actual time=0.027..2488.740 rows=2547647 loops=1)
        -> Temporary table  (cost=7093350.93..7093351.43 rows=6083517) (actual time=21616.863..24280.942 rows=2547647 loops=1)
            -> Nested loop left join  (cost=6484999.19 rows=6083517) (actual time=0.127..12408.895 rows=2547647 loops=1)
                -> Nested loop left join  (cost=336301.25 rows=1446307) (actual time=0.113..5024.664 rows=2547647 loops=1)
                    -> Nested loop left join  (cost=188190.31 rows=1446307) (actual time=0.105..1015.506 rows=2547647 loops=1)
                        -> Nested loop left join  (cost=41177.15 rows=5475) (actual time=0.083..85.897 rows=7747 loops=1)
                            -> Nested loop inner join  (cost=38336.42 rows=5457) (actual time=0.069..43.167 rows=7747 loops=1)
                                -> Filter: ((CV.configuration_value = 1) and (CV.tenant_id is not null))  (cost=137.02 rows=53) (actual time=0.041..1.780 rows=3 loops=1)
                                    -> Index lookup on CV using X_tcv_tenant_configuration_id (tenant_configuration_id='236')  (cost=137.02 rows=527) (actual time=0.036..1.725 rows=527 loops=1)
                                -> Filter: ((users.grp = 3) and (users.`status` <> 8))  (cost=517.94 rows=104) (actual time=0.022..13.537 rows=2582 loops=3)
                                    -> Index lookup on users using X_cu_tenantid (tenantid=CV.tenant_id)  (cost=517.94 rows=2071) (actual time=0.017..11.156 rows=2859 loops=3)
                            -> Filter: (UEI.deleted = 0)  (cost=0.42 rows=1) (actual time=0.004..0.005 rows=1 loops=7747)
                                -> Index lookup on UEI using X_cuei_patient_id (patient_id=users.userid)  (cost=0.42 rows=1) (actual time=0.004..0.005 rows=1 loops=7747)
                        -> Covering index lookup on CV1 using U_tcv_tenant_configuration_id (tenant_id=CV.tenant_id)  (cost=0.44 rows=264) (actual time=0.016..0.095 rows=329 loops=7747)
                    -> Filter: (TC1.configuration_key in ('auxilary_physician_identifier_type','auxilary_nursing_agency_identifier_type'))  (cost=0.00 rows=1) (actual time=0.001..0.001 rows=0 loops=2547647)
                        -> Single-row index lookup on TC1 using PRIMARY (configuration_id=CV1.tenant_configuration_id)  (cost=0.00 rows=1) (actual time=0.001..0.001 rows=1 loops=2547647)
                -> Filter: (UEI.identity_value = up.patient_id)  (cost=3.83 rows=4) (actual time=0.003..0.003 rows=0 loops=2547647)
                    -> Index lookup on up using X_up_patient_id (patient_id=UEI.identity_value)  (cost=3.83 rows=4) (actual time=0.003..0.003 rows=0 loops=2547647)
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