Google owns a 14% stake in AI startup Anthropic and is set to invest another $750 million this year through a convertible debt deal.Google's total investment in Anthropic now exceeds $3 billion.Anthropic's independence is questioned due to its deep ties with Google and Amazon, raising concerns about the influence of big tech in AI startups.Regulators have scrutinized such deals but a recent proposal by the Justice Department to force the sale of some stakes was dropped.