Missing forward slash / for media filepath

There is apparently an issue with the migrator plugin, or you supplied the destination domain in an unexpected way. Either way, consider reporting to the plugin’s devs through their dedicated support channel so they can correct either their code or their domain/path prompt.

Now, how to correct the erroneous URLs? You could redo the import, ensuring you provide the proper domain/path, if that was the issue. Or wait for an update if it’s the migrator plugin itself. Or migrate through a different method.

Or you could patch up the existing data with the Better Search and Replace plugin. After doing this, double check you home and site URL options, they must not have a trailing slash.