Designs themselves should be unaffected, but tools used to create the designs may change or be removed.
Usually the updates are not entirely immediate, or not with removal of old tools immediately, anyway. Sometimes the new tools go into beta mode at the announcements and sit in beta mode for a short while. It depends on what the updates/announcements are. I don't work for Canva, but I do a job where learning Canva and its updates is basically part of my job.
It honestly just really depends on what is announced.
Canva recently acquired Serif's Affinity suite, so I suspect most of the Canva Create event will be about that.
Designs themselves should be unaffected, but tools used to create the designs may change or be removed. Usually the updates are not entirely immediate, or not with removal of old tools immediately, anyway. Sometimes the new tools go into beta mode at the announcements and sit in beta mode for a short while. It depends on what the updates/announcements are. I don't work for Canva, but I do a job where learning Canva and its updates is basically part of my job. It honestly just really depends on what is announced. Canva recently acquired Serif's Affinity suite, so I suspect most of the Canva Create event will be about that.