SIze 0 in pg_stat_file, pg_stat_progress_copy

on a debian machine, with a postgres 14,2 server

logs in a dedicated  directory (not log)

when logged as superuser, I get:

--pg_stat_file for the current logfile says size 0,

--pg_ls_logdir answers 0 files,

--pg_ls_dir, for the log directory provides postgres.csv, postgres.json,... list of files

--and when running a copy from the current logfile with a where clause to choose only the current day logs, the bytes total column is 0

what can provides such a behaviour ?

thanks,