It may be common in your organization to inquire, but consider a change from that because such inquiries with casual questions asked in Whatsapp or IG will not get you reliable information. People leave an organization for all kinds of reasons and all places have politics. It is as useful as asking someone, "What did you think of the Niagara Falls/ Great Wall of China?" Keep it super simple: A new employee is joining. Follow the organization guidelines to welcome them, help them settle in, point them to resources, make it clear how to contact you. Don't spend energy on assuaging vague concerns your team members have about the support they will receive. Instead of anticipating problems of all kinds and preparing for them, wait for an actual problem, and attend to it when it happens.