I don’t have a great answer for this other than “what problems do you/your friends and family have?”
But this might help. Look up various businesses and find out what problems those businesses solve.
Don’t overthink this part, it’s literally the easiest part. This world we live in is plagued with not only problems, but also solutions that aren’t so great and could use competition (like how banks didn’t update their websites and app until they started getting killed by fintech apps that were so much better to use)
I started working on my startup and came up with a way better idea. Like change the world and how people work. I’m not normally the type to drink my own kool aid because it’s a rookie move, but I genuinely love this idea. I’m working on it in the background