Function with text blob return encoding issue with FB30

[EPluribusUnum]

Hi *!

database default charset WIN1250

CREATE DOMAIN XTXTBLOB AS BLOB SUB_TYPE 1 SEGMENT SIZE 80 CHARACTER SET WIN1250 COLLATE WIN1250;
CREATE DOMAIN XVAR100N AS VARCHAR(100) CHARACTER SET WIN1250 NOT NULL COLLATE PXW_HUNDC;
CREATE TABLE kv (KULCS XVAR100N, ERTEK XTXTBLOB);

CREATE OR ALTER FUNCTION kv_list
RETURNS xtxtblob
AS
DECLARE VARIABLE valasz xtxtblob;
BEGIN
valasz = (
SELECT LIST(TRIM(x.ertek), '#')
FROM (SELECT v.ertek
FROM kv v
ORDER BY v.kulcs) x);
RETURN valasz;
END

CREATE OR ALTER PROCEDURE kv_list2
RETURNS (
valasz xtxtblob)
AS
BEGIN
valasz = (
SELECT LIST(TRIM(x.ertek), '#')
FROM (SELECT v.ertek
FROM kv v
ORDER BY v.kulcs) x);
SUSPEND;
END

Using UTF8 connection
INSERT INTO kv(kulcs, ertek) VALUES('1', 'Első sor');
INSERT INTO kv(kulcs, ertek) VALUES('2', 'Második sor');
SELECT LIST(TRIM(x.ertek), '#' ) FROM (SELECT v.ertek FROM kv v ORDER BY v.kulcs) x;--fine
SELECT * FROM kv_list2;--fine
SELECT kv_list() FROM rdb$database;--wrong: Els� sor#M�sodik sor

Wrong with FB30. FB40 and FB50 is fine.

[sim1984]

It seems to be the same as #7604
The fix was not ported to Firebird 3.x.