Might be, but I agree with the comment below.
Which is still stupid because IRL Operations is if any part of Command (or at least an adjutant to it) not Engineering (with the exception of Armory).
Money is basically just a way of recognizing priviledges and we know that different ranks have different priviledges.
That might be the truth. A promotion might give the promoded person better replicators, a better house or apartment on Earth and more pocket money on alien worlds or stations like DS9 where some sort of currency is used.
The vast majority of the evidence suggests otherwise.
Hmmmm....I'm not so sure about that.
Given that he was promoted in role, it seems very likely that he was demoted in rank.
And all this brings us back to if Miles were demoted on the Enterprise and why?
It actually looks like he was!
But was not referred to as "Ensign" and this was specifically retcon'd by All Good Things which included specific dialogue referring to him as a "Chief".
Even disregarding this, he appears as a Crewman (no pip) in his next appearance, so this can be dismissed as a wardrobe error.
Well, "wardrobe error" might be the truth since there have been a lot of such things in Star Trek.
In VOY, Tuvok was constantly changing from Lieutenant to Lieutenant Commander for a while.
However, I must admit that I always tries to come with some more appropriate Star Trek Universe explanation. In Tuvok's case it was all about his weekly Kal-Toh games with Janeway.
If janeway lost, she was furious and demoted Tuvok, if she won the next game, he got his old rank back. In the end he gave up and always let Janeway win, thus keeping his Lieutenant Commander rank.
Maybe Miles got the wrong uniform by mistake and Picard sent him to the brig for a day or so.
PICARD: Crewman! Why in the world are you wearing an Ensign's uniform! That is a severe violation of Starfleet rules and you should know that. But only because I'm so kind and this is your first mission on the ship, I will only give yo one day in the brig. Security! Take him away!
That was probably an error by Frakes as it wasn't in the script, and in any case as a single reference is overwritten by other mentions of him being a "Chief" or "Chief Petty Officer".
Will Riker never makes mistakes!
Not to mention that O'Brien was wearing a Lieutenant's uniform.
He was actually wearting a Lieutenant's uniform from the episode
The Child which took place on Stardate 42073.1 (Wed, 27 Jan 2365 ) to the episode
Realm Of Fear, Stardate 46041.1 (Thu, 16 Jan 2369), more than four years!
The next time he shows up is in DS9's
Emissary Stardate 46379.1 (Mon, 19 May 2369) and is wearing a single black pip which indicates that he is a Warrant Officer.
Now that is a demotion if anything!
So what happened in thise dreadful days between 16 january 2369 and 19 may 2369? What horrible crime or violation of Starfleet rules did poor Miles commit? Or what secrets did he discover?
Actually, it was the fifth season and the only thing that is "obvious" is that it designates one or more (because O'Brien continued to wear it on his dress uniform through at least one promotion) ranks between Crewman and Ensign.
It's certainly not a buck sergeant's insignia.
It's based on a hybrid of the USN/USCG Senior Chief and Master Chief's insignia and appears to designate a Senior Chief (based on dialogue) which is equivalent to a Master Sergeant or Senior Master Sergeant depending on service.
It looks like a Sergeant's insignia.
Nothing, if anything compared to his rank on arrival at Deep Space Nine he was promoted.
I have my doubts since he was seen in a Lieutenant's uniform in TNG then he is not in some episodes after that and then he shows up on DS9 he is a Warrant Officer. That's what I call a demotion!
He doesn't, because that was Tom either trying to make the Chief go away before he broke his cover (or just being bigotted against transporter operators)
Or did Tom simply use what he had heard from his brother Will about a possible conflict or whatever between Will Riker and Miles O'Brien just to get rid of O'Brien from the Defiant because he knew that O'Brien would be too embarrased by bringing some dark secret up in front of Kira?
The mystery just gets more mysterious.