Didn't it start off as pretty clearly & specifically blue
It was always a teal in Season One of TNG. We had Susan Sackett visit Sydney just after the season ended and, when asked about the colour, she picked out an audience member at a gathering and said that her eyes were "Just the right colour." Bluish green.
and got greener with every revision until you hit the ST:FC uniforms, whose undershirt was more green than blue...
Again, it wasn't just a dye variation but was dependent on overhead lights, which can be different for filming and for still shots.
We had a weird experience with DS9 in Australia. We got to see "Emissary" on US broadcast copies on VHS, airmailed by penpals, and then both PAL and NTSC commercial home video copies, and the teal uniforms appeared totally different
in each version! One was a very blue blue, one was a green green, and one was in between.