How do I pin notifications from certain apps so I don't accidentally clear them?

Since I've updated my S23U to One UI 6.0 my To Do app reminder notifications are no longer pinned to the notification tray. I can't seem to find the setting to re-enable this either. Anyone know how to bring this back?

For clarity: By pinning notifications I mean you can't accidentally clear them. Instead, you have to expand the notification and click the clear notification button (which is much less accident prone).