Apparently matches this North and South American species: See iNaturalist: https://www.inaturalist.org/observations/10984571 I assume its an introduced 'pest'of soybean crops in Australia.
Soybeans are grown in the Darling Downs in Qld which roighly corresponds with the INat/ALA record. Also grown further south under irrigation in inland NSW and in to northern Vkictoria, so not unreasonable we can pick up the moth here too. The sort of crop small farmers and backyard growers would experiment with too!
The discussion on iNaturalist for M.ajustipennis suggests they are different species. There is one image by G. Cocks of M. palpigera on the ALA and iNaturalist which I think looks similar, but perhaps slightly different (i.e a dorsal not lateral image). The Australian Faunal Directory does not list M. ajustipennis, but does list M. palpigera, so the Directory therefore does not recognise them as synonyms for the same species. On Bold Systems 4 I do see Mesophleps adustipennis (6 specimens) listed as a species under the Mesophleps genera, but apparently not M. palpigera, There are several other similar looking Mesophelps genera species shown there distributed all over continental Australia. But Bold Systems 4 does not show M. adjustipennis as occuring in Australia. Therefore suggest it would be perhaps better for us to classify this as Mesophelps (genus) for now. PS. I note the taxonomic revision that occurred, See: https://biodiversity.org.au/afd/publication/b2090ff0-83e4-4786-b26d-910173fa4c68 which reverts M. palpigera to a species occuring in Africa. The one M. adjustipennis ID in Australia is hotly disputed on iNaturalist although I do think Bron's sightings do look a lot like overseas M. adjustipennis sightings.