I have realized that I may not be taking Allah as seriously as I should, and that I might not be as scared of him as I should, everytime I pray or make dua, I find myself asking myself in a second perspective “are you even taking this seriously? Do you think this is a joke?” What do I do in this situation

Never underestimate daily prayers. Perform them on time and with focus and reflections and it’ll help you gain certainty InshaAllah