Parse String datetime with Zone with Java Date

You don't even need to define a pattern, your examples are ISO formatted and they contain an offset rather than a zone.

That's why you can use this alternative (if you want to stick to LocalDateTime):

// parse without passing a formatter
OffsetDateTime odtA = OffsetDateTime.parse("2021-12-27T09:15:09.738+02:00");
OffsetDateTime odtB = OffsetDateTime.parse("2022-01-11T20:04:21+02:00");
// extract the LocalDateTimes
LocalDateTime ldtA = odtA.toLocalDateTime();
LocalDateTime ldtB = odtB.toLocalDateTime();
// print them
System.out.println(ldtA);
System.out.println(ldtB);

Result:

2021-12-27T09:15:09.738
2022-01-11T20:04:21

To make your method shorter, write something like this:

public static String getDatetimeFromDatetimeWithT(String dateFull) throws DateTimeParseException {
    return OffsetDateTime.parse(dateFull)
                         .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);
}

This basically parses the String argument to an OffsetDateTime and formats that OffsetDateTime using only the information a LocalDateTime has.

Result stays the same as posted above…

Your date pattern is not correct. Use this:

yyyy-MM-dd'T'HH:mm:ss.SSSXXX

Or use one of the predefined ISO standard classes to do the parsing for you:

DateTimeFormatter.ISO_ZONED_DATE_TIME.parse(dateFull);