What about this query? (https://dbfiddle.uk/ZTFhmLkt)
select id, "timestamp"
from t
where id = 100
and "timestamp" >= '2024-04-19 10:00:00'
union all
select id, "timestamp"
from (
select id, "timestamp"
from t
where id = 100
and "timestamp" < '2024-04-19 10:00:00'
order by "timestamp" desc
limit 1
) as sub
order by "timestamp" desc;
id timestamp
----- ----------
100 2025-01-27 10:00:00
100 2025-01-26 10:00:00
100 2025-01-25 10:00:00
100 2024-04-20 10:00:00
100 2024-03-25 10:00:00