In both the Torah reading and הפטרה of פרשת עקב (from 49th and 50th chapters of ישעיה), we find some examples of when the written word in the Torah or Prophets scroll is the four letter name of God, yet the pronunciation is אלקים. If my memory serves me, this doesn't happen in the first four books of the Torah. The גמרא in פסחים נ עמוד א explicitly says that the four letter name is pronounced with א, ד. Why not just use אלקים explicitly in these places?
There are cases in the navi where the four letter name follows the aleph dalid name. You can also see that the vowels as printed will therefore be the vowels of elokim rather than the usual vowels that are printed with that name (which are supposed to point to the aleph dald name).
The example of this is Yeshaya 50:4, 5, 7, 9 The reason for writing it that way would be because the navi explicitly used the four letter name in that order in his nevua. Thus, we cannot write a different word in its place. All the kri ksiv follows the mesorah. Thus, the way it is written is what the navi specified to be written, while the kri follows the mesorah as to how the navi wanted it spoken.
The reason would be so that the first word of the two word phrase is not repeated, but shows that it is a different word.
Rav Isaac Levy, the grandson of Rav Hirsch, who translated the Hirsch Chumash, translated the Haftarot commentary of R' Mendel (הר׳ רבי מנחם ב"ר שַמשון) Hirsch (Die Haftarot, übersetzt und erläutert, 1896 (2. Auflage 1913)), into English. He added the Haftarot as a final volume to his Hirsch Chumash. He translated the two word phrase in Yeshaya 50 as
My Lord, "the G0d Who Revealeth His Love in administering judgment"
Thus the specific meaning cannot just explicitly use other than the four letter word for Hashem.
Thanks to @NoachMiFrankfurt for the update