It’s very popular indeed, 34m downloads last month, 52nd most popular on PyPI:
Let’s imagine we got control of the existing toml right now and released it today with a warning saying to use some other name we also release.
That gives everyone 10 months to heed the warning and upgrade before toml is released in CPython 3.11.
Compare, CPython requires a minimum of two releases of warnings before removals = 2-3 years, depending on the cadence. It’s often years longer, and yet there’s many packages which never upgrade until the last minute, or after the removal (and some never do, nose is a recent casualty of 3.10 yet many projects are still testing with it).
10 months feels much too short notice for such a popular package.
And realistically, the PEP 541 toml name transfer has another three weeks minimum on the clock plus backlog delays, putting it under 9 months to warn.