Try (for SQL 2017 and up):
declare @input TABLE
(pickno varchar(50),
reasonorshipinstrction varchar(1000),
code varchar(2),
username varchar(45)
)
insert into @input values
('L11230','side cracks','R','Tuli'),
('L11230','Funnel issue','R','Tuli'),
('L11230','Back to date 02/03/2021','S','Deemra'),
('L11230','Completed date changed 03/04/2021 to 09/04/2022','S','Alex'),
('M12401','Random repair ','R','Mina'),
('M12401','allergen','R','Alex'),
('M12401','returned from shop','S','Deemra'),
('M12401','this pickup is scheduled 04/2/2021','S','Tuli')
SELECT pickno, STRING_AGG(CASE WHEN [code] = 'R' THEN 'name-'+ username + ',reason-' + RTRIM(reasonorshipinstrction) END, ', ') AS [reason],
STRING_AGG(CASE WHEN [code] = 'S' THEN 'name-'+ username + ',shipping instruction-' + RTRIM(reasonorshipinstrction) END, ', ') AS [shipping instruction]
FROM @input
GROUP BY [@input].pickno