Do applicants have to submit a separate proposal for the widening call to be considered for this funding?

There is no need to submit a separate application for the widening call. This is the procedure, as described on p.56 of the Widening participation and strengthening the European Research Area Work programme 2021-2022: “In order to apply for the ERA Fellowships call, applicants need to submit their proposal to the Marie Skłodowska-Curie actions (MSCA) Postdoctoral Fellowships 2021. To be eligible to this call the host organisation must be located in an eligible widening country. The application to the (MSCA) Postdoctoral Fellowships 2021 will be automatically resubmitted to this call in case the proposal fails to reach an adequate place in the ranking to be funded. This simplified submission procedure to the ERA Fellowships call presents applicants moving to Widening countries with an additional funding opportunity but there is the possibility to opt out during the application stage.”