Postgres 11

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CREATE TABLE posts  (
    post_id text,
    questions jsonb
);

INSERT INTO posts  VALUES
('70071d97-06a8-401f-abfc-20ddada4f402', '[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question":   "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]');

SELECT * FROM posts 

CREATE TABLE

INSERT 0 1

post_id
questions

70071d97-06a8-401f-abfc-20ddada4f402
[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]

SELECT 1

    SELECT
        questions,
        elems.value
    FROM
        posts,
        jsonb_array_elements(questions) elems

questions
value

[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]
{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}

[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]
{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}

SELECT 2

    SELECT
        questions,
        jsonb_agg(elems.value) AS data
    FROM
        posts,
        jsonb_array_elements(questions) elems
    WHERE
        not (elems.value ->> 'transaction_id' = 'ac547b52-72f3-444e-800c-46aaa48855a5')
    GROUP BY questions

questions
data

[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]
[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]

SELECT 1

UPDATE posts p
SET questions = data
FROM (
    SELECT
        questions,
        jsonb_agg(elems.value) AS data
    FROM
        posts,
        jsonb_array_elements(questions) elems
    WHERE
        not (elems.value ->> 'transaction_id' = 'ac547b52-72f3-444e-800c-46aaa48855a5')
    GROUP BY questions
) s
WHERE s.questions = p.questions;

SELECT * FROM posts

UPDATE 1

post_id
questions

70071d97-06a8-401f-abfc-20ddada4f402
[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]

SELECT 1

questions	value
[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]	{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}
[{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855a5"}, {"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}]	{"question": "TEST QUESTION", "transaction_id": "ac547b52-72f3-444e-800c-46aaa48855ab"}