That address is the published contact for FromHEIC. It is defined in the site configuration so it can be changed in one place. Use it for a correction to the privacy policy or the terms, a file type that fails in a current browser, or a licensing question about the HEIC decoder.
A useful bug report names the browser, the operating system, and the format (HEIC, WebP, or AVIF), and says what the row on the page reported. You do not need to attach the photo. FromHEIC cannot recover a picture you converted, because the picture never arrived here. If a download failed, the file is still on your device. Add it again, or download the single finished row instead of the ZIP.
This page does not send the message through the website. Your mail program does, once you choose to write. The privacy policy explains what the site itself does and does not collect.