If someone is praying and always thinks that: they are doing the prayer wrong, a little of their hair came out of the hijab, they think their feet was exposed, they were 2 hours late for prayer. All of these things make praying hard for them. They put too much pressure onto making everything perfect that they forget to have strong faith. And if someone is reading Quran in a whispering voice and then thinks that their Quran recitation won't be given reward because of some scholars who say to read in a higher volume. That makes the person more pressured and again have less faith. And what if someone doubts all this and thinks that their fast won't be accepted because they didn't read Quran well or they didn't pray well.
What can a person do to not have these thoughts and to put less pressure into making every religion obligation perfect? How does someone have confidence in themselves and trust that Allah listens to them and rewards them for trying?
It is not waswas (devil's whispers), it's more of reading and hearing the rules of scholars and rules of islam in general.