In most cases this is happening because your iPad runs out of memory, especially for more complex drawings. Here are a couple of things that you can try:

• follow steps from this guide → I'm experiencing lag when drawing
• check your internet connection by going to https://fast.com (should show minimum 1Mbps)
• try creating a canvas not bigger then Full HD (1920px x 1080px)

If nothing above helps and you're still experiencing crashes, please contact our support team including following information:

• your iPad specification
• link to canvas when the issue is happening
• (optional) recording showing you opening the application and experiencing the problem