I'd run. If the numbers there are correct, neither management nor investors really have any confidence in the company. As an employee you shouldn't either, particularly for that far under market in cash comp, and if somebody is willing to double your cash compensation, take it.
That is not the valuation of the company, not all shares outstanding are common, some are preferred which are going to have a substantially higher FMV for an early stage.
I don't know what a "normal" multiple/mark-up preferred would normally have at this stage, obviously it varies on terms. 55M shares outstanding this early would not be the sign of a "healthy" cap table unless they didn't start with the standard 10M outstanding.
The parent comment is also correct. We've experienced a down round due to the pandemic.
which is expressed in the preferred share's being valued at 13x the common shares
No its a harmfully naive analysis, your "calculations" put the common shares at 10x their stated FMV.