Jeremiah 25:11 clearly says that "these nations will have to serve the king of Babylon for 70 years" and that clearly means that the verse is saying those nations must become in servitude to Babylon for 70 years. Verses 2-9 along with verses 15-18 indicates that the kingdom of Judah was included in those called "these nations". It is not necessary that the Bible use the specific wording of "70 years of Babylonish domination or servitude" in order convey that idea, provided an expression with the meaning is clearly indicated.
scholar, since you believe the Book of Daniel describes the experiences of an actual person named Daniel, notice what Daniel 1:11-12. There is says that Daniel (in the court king of Babylon) referred himself as a servant of his guardian and the chapter indicates that the guardian was employed by "Nebuchadnezzer the king of Babylon", thus making Daniel also a servant of the king. Daniel 2:48-49 also indicates (according to the Book of Daniel) that Daniel was an employee of the Babylonian king.
But Jeremiah 25:12 is also relevant to helping us to see that the book of Jeremiah says the people of Judah (at least of Jerusalem) were to be exiled for 70 years in Babylon. My first clue to that was the heading of "70 years' exile in Babylon foretold" in the 1984 (bi12-E) edition of the NWT, on page 999 which includes Jeremiah 25:5 -19. In Jeremiah 25:12 the 1984 NWT has a scripture cross reference pertaining to when "seventy years have been fulfilled". The cross reference is to three verses of which one is Jeremiah 29:10. The heading for the page which has Jeremiah 29:10 says in part "Exiled 70 years.". The verse on that page says the following.
' “For this is what Jehovah has said, ‘In accord with the fulfilling of seventy years at Babylon I shall turn my attention to YOU people,+ and I will establish toward YOU my good word in bringing YOU back to this place.’ ' For context, note also that verse 4 of the same chapter says the following. ' “This is what Jehovah of armies, the God of Israel, has said to all the exiled people, whom I have caused to go into exile+ from Jerusalem to Babylon'. Jeremiah chapter 29 is thus very clearly saying that the Jewish people of Jerusalem (the main city of the kingdom of Judah) were to be released from exile in Babylon after 70 years. In case you wondering what "place" (to which the people were return to, according to the Bible) was referred to in verse 10, see verse 1 of the same chapter (chapter 29). That verse says the place was Jerusalem, for it says the following.
"And these are the
words of the letter that Jeremiah the prophet sent from Jerusalem to the
remainder of the older men of the exiled people and to the priests and
to the prophets and to all the people, whom Neb·u·chad·nezʹzar had
carried into exile from Jerusalem to Babylon".