It's only ominous if you believe that Suzu is experiencing genuine fear or discomfort on those last few pages. Which would fly directly in the face of the overall tone the mangaka spent the first half of the story setting up.
Right--that thing about how she keeps changing hobbies then puts "shared hobbies" under preferences indicates that Suzu is pretty oblivious about herself.
(We've all known those people who say, "I'm the kind of person who [______]," and everybody who knows them looks at each other and thinks (or says), "You are so not!")
While the action here fits the minimal technical definition of "catfishing," Kasumi's motivation is simply to get her friend to stop being so oblivious. The longed-for facial expression isn't Suzu's distress or confusion, it's her rethinking her relationship with Kasumi.