There are a few reasons why Facebook Marketplace might keep shutting down on your iPad. Here are a few possible causes and solutions
Your iPad is running out of storage space. Marketplace requires a certain amount of storage space to function properly. If your iPad is running low on storage, it may cause Marketplace to crash. To free up storage space, delete old apps, photos, and videos that you no longer need.
Your iPad is outdated. Marketplace is a relatively new feature, and older iPads may not be able to run it properly. If your iPad is running an older version of iOS, it may be time to upgrade.
You are experiencing a network issue. If you are having trouble connecting to the internet, Marketplace may not be able to load properly. Check your Wi-Fi connection or cellular data settings to make sure that you are connected to the internet.
You are using an older version of the Facebook app. Marketplace is a new feature that is constantly being updated. If you are using an older version of the Facebook app, it may not be able to support Marketplace properly. Update the Facebook app to the latest version to see if that fixes the problem.