Is This Penalty?

It doesn't look like a full penalty since your brand terms still rank and SEMrush shows steady keywords. this could be temporary ranking fluctuation from the recent google update ( also called a google dance). so, give it some time and monitor closely.

Yeah, this sounds like classic Google “update whiplash”, not a full penalty, more like turbulence from the algo recalibrating.
That spike-then-drop pattern right after an update? Super common. Google pushes changes, tests new ranking models live, then dials things back or adjusts based on engagement signals. Sometimes you get rewarded for a day or two… then reality kicks in.