'increasingly serious problem' is correct and usable in written English
This term can be used when something is becoming more serious or difficult over time. For example: "Climate change is an increasingly serious problem that threatens the future of the planet."
Either way, bootlegging has become an increasingly serious problem.
As I wrote here recently, Hong Kong's space constraints are becoming an increasingly serious problem.
These sorts of issues threaten to become an increasingly serious problem, in our view.
In the years during and after the American Civil War, the care of foundling infants became an increasingly serious problem in New York City.
If a body with a statutory responsibility for safe conveyance faces an increasingly serious problem that it acknowledges openly that it does not understand, it is obliged to take immediate action.
There have been more raids on domestic poultry and on young pheasants, for instance, and predation on the ground-nesting and very rare capercaillie is an increasingly serious problem in some areas.
Year by year, the company consisted of increasingly young people facing, without the old-timers' guidance, increasingly serious problems: debt, dissension, cold reviews, defecting funders.
Some Western politicians are already threatening us with not just sanctions but also the prospect of increasingly serious problems on the domestic front.
Owing to the increasingly serious problems caused by multidrug resistance in community-acquired infection pathogens, it has become an urgent need to develop new classes of antibiotics for overcoming the resistance.
"Some Western politicians are already threatening us not just with sanctions but also the prospect of increasingly serious problems on the domestic front...
Wang struggled through two years of increasingly serious problems at home and school before he was diagnosed with "Internet Addiction Disorder" and sent to the Qide Education Center in the Chinese capital, Beijing.
