Is severe illness a sign of God's wrath or pleasure? And does weakness of faith, due to the inability to frequently supplicate and pray, despite performing the obligatory prayers on time, indicate God's displeasure?

The pain and illness that afflict a believer are good for them. If they endure patiently, they will receive a great reward. It may also be an expiation for previous sins or a raising of their status with Allah. It is not permissible to wish for death; rather, one should supplicate: "O Allah, keep me alive as long as You know life is better for me, and cause me to die if You know death is better for me." And whoever seeks to be patient, Allah will make him patient.