Ask HN: Good leaver equity - problem for investors?

I co-founded a startup with 3 other co-founders. One of them will be leaving the company - as we have vesting, he still owns about 12% of the company. cap table before leaving: manager1: 24% manager2: 24% manager3: 24% -> is leaving and vest to 12% manager4: 15% Investor1:10% investor2: 3% Our CFO said there would be no chance to get into the next financing round (VC for example) if he would take the full 12% and we would have to cut it down to 5%. The leaving co-founder doesn't see a problem. Is it really a problem for Investors/VCs? Why? Would they rather not invest? Should we stop contacting VCs till we got this issue sorted out? (We are running out of money in 3 months) Your kind help is appreciated! links/books/contacts/literature appreciated