For those using monorepos, what is your branch strategy? Say that 3 projects share a library, and release on different schedules. How does each project freeze

For those using monorepos, what is your branch strategy? Say that 3 projects share a library, and release on different schedules. How does each project freeze shared library changes? Do you keep N version branches? How does the library team know which consumers a commit may break? What tools are recommended?