so i was wondering if the TNG's tone or outlook changed when communism collapsed in eastern europe, since the show was only mid way through its run when it happened.
There is an emphasis that shifted, but not exactly in TNG. TNG early on seems to imply - specifically in the pilot episode and some of early season one - that we simply outgrew the capitalism/communism debate and found it as worthless an excuse to wage war as religion. That's not before our situation got a whole lot worse with drug-addicted soldiers and kangaroo courts (fitting
Star Trek's shifting but oddly consistent vision that while our distant future is bright, our near future is apocalyptic), but hey, we got the general message okay.
There's also a general condescension towards capitalism when the subject is brought up in the first season, be it the contempt shown for the financier in "The Neutral Zone", or the grubby, capitalistic and at this point villainous Ferengi in "The Last Outpost." This attitude isn't as pronounced in any of the subsequent seasons, so vilifying capitalism was the least of TNG's priorities when the Cold War ended... and, again, this doesn't quite equal support of communism either. We've outrgrown 'em both, after all.
The Klingons, who were more-or-less analogous to Cold War enemies in the original series, were now seen as our friends - and while there's one episode, "Samaritan Snare", that suggests they were absorbed into the Federation, TNG's view eventually was there was this peace treaty and we evolved out of our squabble with the Klingons as we tended to do. This meant that, with the Cold War still more or less in-effect, the new stand-ins for the conflict were the Romulans (who had taken the role on TOS occasionally anyway).
But then the Soviet Union collapsed and we got a
Star Trek movie depicting a similar fallout in the Klingon Empire. So peace became a necessity for the Klingons due to their weakness. TNG never engaged the collapse of the Soviets as directly as that film did, however, so I wouldn't overestimate the importance of this event to the series. You could argue that the "Unification" has some relevance to the post-Cold War environment - it deals with Romulans, our Russian proxies by TNG, possibly undergoing a transformative event in their culture - but you'd be really,
really pushing it.