I would’ve had the writers clarify what rank Chief O’Brien actually was earlier on – in TNG he was seemingly a lieutenant who was transporter chief, in the novelisation of DS9 pilot Emissary he was apparently an Ensign Junior Grade(!), and later on in DS9 we get it near enough confirmed he was a senior chief petty officer (or near enough), with chevron-based rank badge.
The only people that ever suggested that O'Brien was a Lieutenant were TNG's
wardrobe department (and a single unscripted slip of the tongue by Jonathan Frakes once), when they gave him the two pips of a lieutenant in his third appearance (after him wearing a single pip as the unnamed CONN, retcon'd as
Chief Miles O'Brien in
AGT) and no pip as an unnamed security guard in his second appearance), despite him being listed as "Transporter Chief" not "Lieutenant" or similar
and the option of a single black pip (his correct rank no later than
Family) being established for Miss Gladstone (a sciences specialist in the
E-D education department), in the
same episode which he appears for the first time as "Transporter Chief".
IMO, while wardrobe details (even if
not present in the script) can be taken as canon, they are trumped by
scripted dialogue if it appears in the aired episode, so the references to O'Brien being a "Chief Petty Officer" during
Family (particularly as it was the first scene written for
Miles O'Brien specifically rather than the generic Transporter Chief who happened to be played by Colm Meaney), particularly as
All Good Things establishes that CONN
was Chief O'Brien as Captain Picard refers to him as such through out the past scenes of the finale, rather than the generic CONN or as Mister O'Brien, which would cover a variety of different options.
O'Brien's rank was always an inconsistency that was never fully resolved. DS9 tried with his unique pip and his 'senior chief specialist' line when he said how his father introduced him to people. But it really felt like it became a sort of inside joke in the franchise.
IMO, if anything the "inside joke" was the extent to which some fans will obsess over and advocate for the tiniest detail even the
vast bulk of the evidence supports a different conclusion if anything.