Postgres: "show max_connections;" output a different value from postgresql.conf file
As the current value is stored in postgresql.auto.conf, it was changed using ALTER SYSTEM and thus has priority over any value in postgresql.conf.
You can either use ALTER SYSTEM again to increase the value:
alter system set max_connections = 250;

which will adjust the value stored in postgresql.auto.conf
Or you can remove the entry from postgresql.auto.conf by using:
alter system reset max_connections;

Then the value from postgresql.conf will be used.
In either case, you have to restart Postgres to apply the new value.