BUG #18438: regex isnt working for "^" , ".*"

The following bug has been logged on the website:

Bug reference:      18438
Logged by:          Ankur Kumar
Email address:      ankurawesome37@gmail.com
PostgreSQL version: 14.5
Operating system:   macos ventura version 13.5
Description:

hey , i am getting empty query result while using postgres regex operator
"^" , ".*" etc . I am able to use "%" correctly but not getting any response
for  other regex operator . For example - There is a user in users table
with  >  first_name - "aman", last_name -  "kumar" .
But while quering  i am not getting any result while querying users table
->

1) SELECT id from users where concat(users.first_name, ' ', users.last_name)
ILIKE '^am' 
2) SELECT id from users where concat(users.first_name, ' ', users.last_name)
ILIKE 'am.*' 
3) SELECT id from users where concat(users.first_name, ' ', users.last_name)
ILIKE '^am%' 

Above queries didnt return any result 

But it works for this query -

SELECT id from users where concat(users.first_name, ' ', users.last_name)
ILIKE 'am%' LIMIT 100