If you accidentally deleted a note within the past 30 days, you can potentially recover it through a couple different avenues.
linkOn desktop: the "Deleted" label in three-pane view
Expand your desktop view so that you can see all three panes. A "Deleted" folder will be available below your tag list.
group: deleted tag
If you enter
group:deleted within your Amplenote search bar, you will see notes that have been recently deleted on the current device
linkOn mobile: expand options to see "Deleted" option below tag list
Tap the triple line in the upper-left of your app to expand the sidebar area. The "Deleted" label is at the bottom of this list.