'decreased popularity' is correct and can be used in written English.
For example, you could use it in a sentence such as: "As the years went by, the show's decreased popularity led to its cancellation."
The skepticism partly reflects the decreased popularity of white bread in the United States.
The results indicate that certain credits do experience decreased popularity among hospitality projects, yet guest comfort was not the only barrier identified.
More convenient than the larger two-cent bronze piece, it largely replaced that coin, starting the two-cent on its way to decreased popularity and abolition in 1873.
As public libraries continue their quest to stay relevant in the wake of cuts to their funding and decreased popularity, some are greatly altering their set-ups and making moves to appeal to a younger crowd.
Laparoscopic fundoplication, while currently considered the gold standard alternative to medical therapy, has seen decreased popularity mostly due to recurrent symptoms requiring medical therapy and the associated troublesome side effects such as dysphagia and gas bloat [ 4, 5].
Apple only sells smartphones, so its fortunes rising in lockstep with the decreasing popularity of feature phones makes perfect sense.
We find that reporting pain is associated with decreasing popularity – interestingly, this effect holds for males only.
DeSoto died a slow death in the 1950s owing to decreasing popularity and the 1958 recession.
However, because of the decreasing popularity of disco, the Academy eliminated the award category before the 1981 ceremony was to be held.
Using repetition, or stuttering, will definitely decrease popularity level.
The scheme was highly popular in the 1980s but as the discounts decreased its popularity faded.
