The darker tone of the fourth season of "Emily in Paris" is primarily due to the delayed filming schedule caused by the 2023 WGA and SAG-AFTRA strikes, which pushed production into the winter months.
While the series isn't expected to completely abandon its lighthearted nature and turn into a "noir" drama, the shift to a winter filming schedule inherently impacts the overall look and feel of the show. This naturally introduces a moodier and potentially more subdued aesthetic compared to the sun-drenched visuals that characterized earlier seasons.
In essence, the strikes' impact on the production timeline resulted in the filming taking place during a darker, colder time of year, which translates into a darker visual presentation for the series.
