And my guess is your clip there is either log-encoded or an HLG "HDR" clip.
So check the clip properties in the bin. If it is HLG, for most purposes you will still want to work in SDR, standard dynamic range, the Rec.709 standards of still the vast majority of media today. If so, right-click one or more clips in the bin, then Modify/Interpret Footage" and set the Color Management options at the bottom for Override to Rec.709.
Then in the Sequence settings, make sure the CM is set to Rec.709. And make sure the Scopes are also showing a Rec.709 signal by right-clicking in the scopes panel, selecting the color Rec.709 color space. Then set the scale dropdown in the lower right corner of the scopes to 8bit or 10bit.
Neil