`tracing_checks` was removed from crates.io for transitively including malicious code

This is part of an ongoing campaign to attempt to typosquat crates in an
attempt to exfiltrate Polymarket credentials.

The malicious crate had 1 version published on 2026-02-26 approximately 9 hours
before removal and had no evidence of actual usage, both in terms of downloads
and dependents. It did not include the malware payload itself; this was instead
delivered via the `tracings` crate, which has received a separate advisory.

Thanks to Marko Ćupić for finding and reporting this to the Rust security
response working group, and to Emily Albini for co-ordinating with the
crates.io team.

The crates.io team advises anyone developing with Polymarket to review
dependencies carefully. We are investigating ways to mitigate this attacker who
appears to be very motivated to steal Polymarket credentials.