zkSync, an Ethereum zero-knowledge (ZK) layer-2 scaling solution, has come under fire for its recent zkSync (ZK) token airdrop, accused of inadequate Sybil filtering measures and fostering an environment ripe for exploitation.

Criticism mounted after Mudit Gupta, from rival Polygon's layer-2 network, lambasted zkSync's airdrop as potentially the most "farmed airdrop ever," citing glaring deficiencies in anti-bot safeguards.

Gupta pointed out, "Almost no Sybil filtering as far as I can see," highlighting vulnerabilities that could allow malicious actors to exploit the airdrop criteria easily.

zkSync had announced that 695,232 wallets were eligible to claim ZK tokens, accompanied by a set of seven criteria aimed at mitigating Sybil attacks. However, industry observers, such as Cinneamhain Ventures' Adam Cochran, criticized these measures as inadequate and conducive to exploitation.

Further scrutiny revealed that crypto analytics firm Nansen clarified its role, indicating it did not conduct anti-Sybil checks but provided data on wallet segments, including whales and known scammers.

In contrast, zkSync defended its approach, arguing against strict Sybil detection measures, suggesting such measures could inadvertently exclude genuine users.

The controversy intensified with claims from Sybil-tracking accounts, estimating that up to 135 million ZK tokens could flow into wallets flagged for Sybil behavior, potentially amounting to $52.3 million based on market prices.

Following zkSync's airdrop details release, the ZK token experienced a significant 43% drop in value on both Aevo and PancakeSwap markets, reflecting market reaction to the controversy.

At the time of reporting, Matter Labs, the development firm behind zkSync, had not responded to requests for comment on the unfolding situation.