Perception of being a "job hopper"?

1. Yes, this is a real thing. If you have multiple stints on your resume that are less than 12-14 months, you may get negative judgment from the recruiter or hiring manager.
2. In terms of harm to a candidate, it won't often come up on your technical interviews. Most of the "standard" interviews, like DSA and behavioral rounds, are focused on assessing your interview performance, they won't ask too much about your resume.

If you do have multiple short stints, come into the calls with the company with a good explanation of why you left and what your motivations were.

Also note that both extremes are possible: you can be at a company for too short a period, and you can be at a company for too long. I put additional thoughts about how long to stay at a company in this YouTube video.