A shared meal can contain several private reasons for being grateful.

Around one table there may be somebody glad to be eating, somebody glad not to be alone, somebody glad that a difficult week has ended and saying nothing about it. The occasion looks like one thing and is really several, running in parallel and mostly unspoken. No one needs to disclose their reason for the meal to work. Knowing the other reasons are there does change how you sit in it.

At the next meal you share, assume at least one person present is grateful for something you know nothing about. Asking one gentle open question, and letting the answer be short, is usually enough.