With Canon's and Nikon's professional camera offerings now being also mirrorless, there are a couple of differences we have to appreciate that is also largely beneficial to professional photographers who are making the switch to mirrorless camera systems and one overlooked feature is the electronic shutter system over more traditional mechanical systems found in DSLR camera bodies.
Having an electronic shutter, like those found in the Nikon Z9 and Canon R3, proves to be highly beneficial. Not only do they increase the burst rate, sometimes up to 30fps and maximum shutter speed to around 1/32000 in the Nikon Z9 and 1/64000 in the Canon R3, but also what it offers for those who shoot flash.
If you were to shoot regular flash on a camera system that has a mechanical shutter, you would be limited to a specific shutter speed when using flash (sync speed). But now with an electronic shutter, there is no such limit. So you'll always have the benefit of shooting HSS (high synch speed flash) as well as having the full ability to control depth of field and mixed lighting environments.
Take a look at the video below by the YouTube channel: DPReview TV on the Canon R3 Final Review...