At exit the preferred shares become common, and the common shares increase in value accordingly. I've seen even series E companies that kept their common share price to under 20% of the preferred share price. If you started on day X with a common share price of 20% of the last preferred share price, and the company was acquired on day X + 1 at a discount, say 60% of the last preferred share price after factoring in liquidation preferences, then your profit from the options is still 2x the strike price.

Loom is an odd case because the timing of their last round was simply perfect. It was announced in May 2021, which means the terms would've been set in Jan or Feb, when Tiger and other firms were on a rampage and competition to get into rounds was at its height. That last $130m has to have been on very favorable terms, not just the valuation but e.g. no crazy liquidation preference. So, unless Loom's founders made some inexplicably bad deals, I'd expect even recent hires to still make a little money. Nobody should be getting zeroed out.