Slow timestamp query after upgrading from Pg13 to Pg16

Hello

After upgrading a Db from Pg13 (Centos) to Pg16(Ubuntu) some queries on
a simple, large table (200M rows) are very slow

id integer not null
status char(4) not null
status_tstamp timestamp
<... other columns ...>

If I create indexes on

* status, status_tstamp
* status_tstamp when status_timestamp is not null

Queries for a set date range for a given status are good and perform
similarly to Pg13

Queries for a set date range are VERY slow compared to Pg13. A few other
queries on tables with indexes like

CREATE INDEX table_col ON table (col) WHERE col IS NOT NULL;

also appear to be slow.

Any ideas, observations or comments would be appreciated

Simon

--
Simon Windsor

Eml:simon(dot)windsor(at)cornfield(dot)me(dot)uk
Mob: 0755 197 9733

“There is nothing in the world that some man cannot make a little worse and sell a little cheaper, and he who considers price only is that man's lawful prey.”