With a trivial Cargo.toml as generated by cargo init, the cargo +esp espflash flash command fails with an immediate error:
Error: cargo_espflash::invalid_workspace
× The current workspace is invalid, and could not be loaded
help: Ensure that a valid `Cargo.toml` file is in the executing directory
If edition is put back to 2021, this error does not happen (though of course other errors do since this is not really a valid esp project).