How do you know who it is not or is, other than yourself?
None of us know who it is. My guess is that it is someone paid with shares. Either for good or services. You know some are being paid their salaries with shares. They may now have to do some selling for their own expenses. Like food and rent.
There are a large amount of shares "overhanging" the market. IMO. The pps can do nothing until these are disposed of. We will be lucky if the pps holds, actually. IMO.