COPY FROM appears broken in PostgreSQL 15

I used to run scripts to process and load data from files into various PostgreSQL tables. A series of:

copy {schema.table} from '/{path}/{file}' delimiter '|' null '' ;

in PostgreSQL 15 it fails with this message:

ERROR:  could not open file "/{path}/{file}" for reading: Permission denied
HINT:  COPY FROM instructs the PostgreSQL server process to read a file. You may want a client-side facility such as psql's \copy.

I have checked and the postgres user can read/write to the file just fine.

In PostgreSQL < 15 it works just fine.

The official PostgreSQL docs, up to and including 16, don't mention a problem with this command.

Did something happen?

Thanks, 

rik.