Using Etcher on a fully updated Solus Budgie system (Etcher version 1.18.13) I get an error when trying to flash an .iso to usb - "Error Opening Source - Something went wrong when trying to open <source>.iso - Error: requestMetadata is not a function."
On the balena-io/etcher github site the same error message is listed as issue #4138 for Kubuntu 23.10, and the workaround used in that instance is to remove gconf dependencies when building Etcher.
Just pointing out that the error is reported on the Etcher github, but not sure if the same workaround would apply in Solus.
I downloaded the Etcher AppImage from their website, which is version 1.18.11. I was able to flash the .iso to my usb drive without any errors.
Thank you, --TonyK.