"Alpha bleed" (or "alpha decay") are commonly used terms in finance and trading to refer to the loss of a trading strategy's "alpha," or the Excess Gain it generates over a benchmark. These terms suggest a gradual decline or leaking away of a strategy's positive performance characteristics, which is often due to increased market pressure, increased competition (i.e. crowding), or changes in market conditions. In this sense, "alpha decay" and "alpha bleed" are similar to "edge decay" and "edge erosion" as they refer to a degradation in the effectiveness of a trading system or strategy.

Reducing Alpha Decay with AI Predictive Signals - Exegy

Standing Out from the Crowd: Measuring Crowding in Quantitative Strategies (Digest Summary)