Functional Source License (FSL)
A licence from Sentry that permits everything except building a competing product, and turns into Apache 2.0 or MIT after two years.
Sentry moved to the Business Source License in 2019, but the BSL leaves both the change date (up to four years) and the additional use grant to each project, so two BSL licences can mean entirely different things. The FSL, released in November 2023, fixes the knobs: the restriction covers competing use, and every release goes permissive two years after it ships.
It comes in two flavours, with Apache 2.0 or MIT as the destination. Internal use, research and consulting work are all allowed. It isn't open source under the OSI definition and doesn't pretend to be; instead it became the template for the Fair Source label a year later. The code is free, just not yet.