Star Trek: Picard season 2's trailer revealed the first look at Q (John de Lancie), who looks curiously older than he did in his appearances in Star Trek: The Next Generation. Q's return is one of the most anticipated aspects of Star Trek: Picard, especially now that Jean-Luc (Patrick Stewart) has returned to action, saved the galaxy, bid a farewell to the late Commander Data (Brent Spiner), and received a new android body.
To Picard's chagrin, he and Q have been inexorably tied together since the very start of Star Trek: The Next Generation. They both debuted in TNG's pilot, "Encounter at Farpoint", where the omnipotent being tried Picard and the crew of the USS Enterprise-D for humanity daring to explore the final frontier. Q was also present for TNG's finale, "All Good Things", which saw Picard face three alternate timelines that were destroying reality. Of course, in between, the all-powerful trickster repeatedly popped onto Picard's starship and pestered him. Not to mention, Q is responsible for introducing the Enterprise to the threat of the Borg. Q has also appeared on Star Trek: Deep Space Nine, Star Trek: Voyager, where he transferred his fixation to Captain Kathryn Janeway (Kate Mulgrew), and even Star Trek: Lower Decks. But still, Picard and Q are forever bonded, and no one captured the immortal space god's fancy like "Mon Capitaine".
In Star Trek: Picard season 2, Q's reappearance is extra significant since he looks considerably older, which is odd for an immortal who never ages. But the reason why Q aged himself is reflected in his words to Jean-Luc: "Oh dear. You're a bit older than I imagined". Evidently, Q decided to age himself appropriately to match Picard, who is now about 95 years old in Star Trek: Picard season 2, which is either set in the year 2399 or it's 2400 and the timeline has already crossed into the 25th century. This actually isn't an unusual thing for Q to do: the omnipotent being has always opted to don a Starfleet uniform when he came aboard the Enterprise, and it always infuriated Captain Picard. Further, Q has always regarded Jean-Luc like a pet so he alters his appearance to reflect his favorite lesser being, in an inverse of how it's often said a pet can start to resemble its owner.
Of course, the real-world reason why Q looks older is that over 25 years have passed since he has seen Picard and John de Lancie has aged, just as Patrick Stewart and the rest of the TNG cast have. But Star Trek: Picard's solution for explaining Q looking older is simple, ingenious, and totally suits the irrepressible prankster. In a way, it's a sign of respect and an endearing move that Q aged himself to make Picard feel more comfortable about his own mortality. Perhaps Q has matured in his time away. It's also interesting that Q's surprise over Picard growing older indicates that he has left Jean-Luc alone and not pestered him since the days Picard commanded the Enterprise-D on TNG.
None of this to say that Q will maintain his older look. Star Trek: Picard season 2 is a time travel story where the Star Trek timeline is "broken" and Q provokes exploration of the "roads not taken" by Picard and his new crew. There is certainly a chance that the show will employ digital de-aging technology to make Q (and possibly Jean-Luc) look 25 years younger to resemble how they appeared on TNG. There may also be a further twist involved that could explain that Q really has aged against his will. But young or old, it's exciting to see Q again, and Star Trek: Picard season 2 should bring back plenty of fond memories as Q taunts Jean-Luc through this new time travel adventure to save the future.