I fail to reproduce the above in SQLite 3.36.0:
<pre>simon@183 Desktop % sqlite3 test.db
SQLite version 3.36.0 2021-06-18 18:58:49
Enter ".help" for usage hints.
sqlite> CREATE TABLE IF NOT EXISTS "series" ( "id" INTEGER NOT NULL DEFAULT 1 PRIMARY KEY AUTOINCREMENT UNIQUE, "acqtime" TEXT );
sqlite> INSERT INTO "series" ("id","acqtime") VALUES (1,'2021-01-02T22:33:44');
sqlite> INSERT INTO "series" ("id","acqtime") VALUES (2,'2021-01-03T01:12:23');
sqlite> INSERT INTO "series" ("id","acqtime") VALUES (3,'2021-01-03T01:02:41');
sqlite> INSERT INTO "series" ("id","acqtime") VALUES (4,'2021-01-03T01:47:55');
sqlite> .mode table
sqlite> SELECT * FROM series;
+----+---------------------+
| id | acqtime |
+----+---------------------+
| 1 | 2021-01-02T22:33:44 |
| 2 | 2021-01-03T01:12:23 |
| 3 | 2021-01-03T01:02:41 |
| 4 | 2021-01-03T01:47:55 |
+----+---------------------+
sqlite> SELECT DISTINCT date(series.acqtime)
...> FROM series
...> ORDER BY date(series.acqtime) DESC;
+----------------------+
| date(series.acqtime) |
+----------------------+
| 2021-01-03 |
| 2021-01-02 |
+----------------------+
sqlite> SELECT DISTINCT date(series.acqtime)
...> FROM series
...> ORDER BY date(series.acqtime) DESC
...> LIMIT 1 OFFSET 400;
sqlite></pre>
I get the expected zero-row result to the above SELECT whereas the OP says he gets four rows. Did I misunderstand the query ?