The phrase "serious downsides" means there are significant negative consequences or disadvantages to something.
Sentences with «serious downsides»
But the controversial procedure is still in the early experimental stages, experts warn, and comes with serious downsides. (health.com)
We also have substantially increased our position in disaster insurance... We continue to be willing to give up a portion of our upside to protect against serious downside exposure. (novelinvestor.com)
But refinancing can come with some pretty serious downsides, so it pays to keep those in mind as well. (studentdebtwarriors.com)