vacuum process running for more than 2 days, still in scanning heap phase

All;

We have a vacuum process that has been running for 2 days, the table is
12GB in total size and vacuum_cost_delay is at 0

The process shows as active in pg_stat_activity, and pg_blocking_pids
returns no blockers

select pg_blocking_pids(1581295);
 pg_blocking_pids
------------------
 {}
(1 row)

A select from from pg_stat_progress_vacuum where pid = 1581295; shows
the phase as 'scanning heap' and the heap_blks_total, heap_blks_scanned,
max_dead_tuples and num_dead_tuples  have shown the same values for at
least the past hour

pid                | 1581295
datid              | 16398
datname            | prod_server_1
relid              | 22532
phase              | scanning heap
heap_blks_total    | 571437
heap_blks_scanned  | 344577
heap_blks_vacuumed | 0
index_vacuum_count | 0
max_dead_tuples    | 155388267
num_dead_tuples    | 199013

We actually tried a pg_terminate_backend on it and it does not die

Thanks in advance for any advice