More crypto exchanges are allowing cryptocurrency investors to earn yields on pledged stakes using newly minted tokens as a reward for helping blockchains transition to a faster, cheaper and greener validation technology known as proof-of-stake. The most widely anticipated of these transitions is the upgrade to Ethereum 2.0, slated to be completed in mid-September after suffering several delays. Rather than relying on the current proof-of-work model, which requires solving complex mathematical problems, proof-of-stake allows validators to stake a minimum amount of crypto to earn a reward for properly validated transactions, or risk losing their tokens. Some exchanges are now offering…