The first thing one should do upon getting an iOS device - iPhone or iPad - is go to Settings > Camera > Formats, and choose Most compatible. This will cause the device to save images as JPG's (and videos in MOV format).
By default, iOS devices store images in the HEIC format. This is an Apple proprietary format. It is complex and patent-encumbered. Even Safari didn't support HEIC images natively until the advent of Safari 17. No other browser supports the format, and there's no evidence that they intend to do so in the future.
The only advantage of HEIC is that it saves storage space. It isn't higher quality, or less lossy, or somehow "better." For most users, storage space is no longer an issue. Available bandwidth is steadily increasing, and SSD drives can be had for less than $50 per TB. It remains an issue only if you store large numbers of original images on your phone, rather than letting them reside in the cloud.
jAlbum can process HEIC images, but the scaling operation typically takes considerably longer than it does for JPG's. And of course, since the images are destined for browser viewing, they have to be converted to JPG, anyway.
Support for HEIC images in other applications is spotty. Some image processing packages, for example, can read an HEIC image, but can't save an image in that format. So, once you've done your image editing, you'll have to choose another format in which to save the result.
There have also been reports of HEIC images losing their metadata - camera shooting information and GPS coordinates - when they are converted. This seems to be dependent upon how the conversion is done, and in what application. If the phone stores its images as JPG's, rather than as HEIC's, this does not happen.
Additionally, the metadata extractor used by jAlbum also has problems if the HEIC has been edited within the Photos app, even if it's still exported as an HEIC image.
Support for the competing AVIF format is broader, and that format is royalty-free. Support for the more feature-rich JPEG XL open standard is still very limited. jAlbum does not support either format.