The updated extension API entrypoint from DuckDB v1.4 will require some work from many community extension maintainers. We'll automatically create an issue in the affected repositories pointing to this issue.
The easiest way to understand what needs to change is to look at the extension template PR that applies the changes.
If you want to prepare your extension before the DuckDB v1.4.0 is out, check out this example on how to use ref_next
in the PR where the quack extension is bumped: duckdb/community-extensions#548