By default, PhotoRoom exports images in .png to ensure that no quality is lost when exporting.
In PhotoRoom, you can go to "Your Content" tab and then "Preferences", you can enable "export in .jpg". It will export images that are smaller in storage space but can sometimes be of lower quality. The setting is saved and will be applied to all your future exported images.
Please note that this setting is currently not shared through your team(s) and not shared through your platforms. You need to set it individually per team member and once per platform (web, iOS, Android).