A mantis strike is powerful for its size, and the raptorial forelegs close in a few tens of milliseconds with spines that lock the prey in place. That apparatus is built for insects, but a hovering hummingbird weighing three to four grams sits within the range a large mantis can hold.
An ornithological review compiled dozens of documented instances of bird capture by mantises worldwide, spanning multiple mantis species and many bird species. The great majority came from the United States and involved hummingbirds, and most occurred at or beside artificial nectar feeders, where mantises can wait beside a reliable stream of visitors. The Chinese mantis, introduced and abundant in that region, features repeatedly.
The concentration at feeders is the important qualifier. It suggests the interaction is heavily shaped by a human-created situation that puts a predictable small bird within reach of an ambush predator, rather than reflecting a natural component of the mantis diet. Whether mantis predation has any measurable effect on hummingbird populations has not been demonstrated.