Ah, so common lah! A few of us went through this, sometimes they forget how to chew properly or just get lazy, especially if they've been on softer foods for a bit. Try cutting meat into smaller pieces first and let him see you chewing and swallowing (kids copy!), and maybe dip it in gravy or sauce so it slides down easier while he learns. You could also offer softer fruits like banana or pawpaw alongside the harder ones, then gradually mix them so he gets used to it again, some of my mum friends found that doing meals together (whole family eating the same thing) really helped their toddlers stop spitting out lumps. If he's still really struggling or seems uncomfortable, best check with your doctor just to make sure there's nothing going on with his chewing or swallowing, ok?