GIN index operator ?(jsonb,text) not working?

Hi,

dbfiddle: https://dbfiddle.uk/?rdbms=postgres_14&fiddle=060af497bbb75ecddad9fd2744f8022b

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create  table test101 (  doc_id bigserial, document jsonb);
insert into test101(document) values ('{"user_removed" :false}') returning *;
insert into  test101(document)  select '{"user_removed" :false}'::jsonb from generate_series(1,10000);
insert into  test101(document)  select ('{"user_remove"  :false, "test":' || i ||'}'::text)::jsonb
                                from generate_series(1,400) i;

CREATE INDEX test101_gin_user_removed_na ON test101 USING GIN (document jsonb_ops)
    where (document ? 'user_removed') is false;

CREATE INDEX test101_gin_user_removed_na_b ON test101(document)
    where (document ? 'user_removed') is false;

Since 400 is very few percent compared to 10000. 

but the following query will not use any of the indexes.

    explain (analyze)  select * from test101 where  document ? 'user_removed' is false ;