Typically a shrinkwrapped record is tight enough to keep the LP from sliding around. If you sold it as sealed you need to ship it as sealed.

I don't recall a sealed record that showed up with a split spine. And I've ben dealing with records for literally 30 years.

It's the records shipped with the vinyl in the jacket that isn't shrinkwrapped, especially frustrating with a small label from the early 2000's and the record store that distributed the releases shipped them in the jackets, not wrapped. So know all these $500 records had split spines right out of the box

also, I pack all records in a quality LP mailer with 2 cardboard inserts, and when it's a used record a square of bubble wrap on the side where the actual record is. Never, ever have I had an issue.