I haven't looked at a 2020 ski yet... but everything I have put my hands on uses a carbon ring.
Seadoo changed to that design in 1995. They don't (potentially) last as long as a "Stuffing Box"... but they are safer. Here's the deal. A standard seal pack has an inner, and outer seal, and a bearing of some kind in the middle that keeps it centered on the driveshaft. It's held in place with a rubber boot, and some clamps. (kind of like a carbon seal) There is also a grease nipple. Most people are lazy, and just beat the hell out of their PWC, and don't actually maintain them. So... water gets into the seal pack, and rusts the bearing. While out running... that bearing seizes, and stops... but the shaft doesn't. The pack spins... rips the boot, and that leaves a 2" hole in the bottom of your ski. It will sink in about 10 seconds.
The other side of it is... someone that doesn't understand how to properly maintain things, and when the book says "One pump of greases after 10 hours" thinks.... "Lets pump it 5 times". The problem with this is... HYDROLIC PRESSURE !!! So 5 pumps will build pressure, and can literally push the seals out of the pack. No seal... and you get the same issue as above.
If maintained... a seal pack can last dang near forever. I had one in my Polaris that was 15 years old, and working great... but I rebuilt it because I had the shaft out.
Carbon seals wear out... leak, and make it so you can't leave your ski or boat in the water... but they CAN NOT have a catastrophic failure.