It's always a pain in the ass when you discover your phone has actually been saving your photos as heic or webp or avif or whatever and hardly anything will open them.
I could understand wanting to improve JPEG in the age of dial-up and 1.44MB floppy disks - 60% smaller images could have been a great benefit in those days. But today, even if I'm taking 30 photos every day at 4k resolution, it'd take 20 years to fill up a $50 1TB disk.
The other benefits of the format might be great for some specialist applications, but options like billion-pixel-wide images, 32 bits per channel and 4099 channels ready for medical imaging only get a shrug from me. I doubt my browser is going to start displaying 4099 channel images.
I just wish we could get rid of heic, webp and avif at the same time.