Today I found out I might have been washing my face wrong in wudu. As a result I became angry because I had to redo my salat and because I felt like I should have known this ruling. Am I sinful for this anger, it is most likely I became angry due to salah being stressful on me due to waswas.

Ustadh AbdulAziz al-Haqqan

The real matter here is the waswas, so do not let it make your salah a burden, take the easier way and disregard these doubts, and in sha Allah your prayer is sound.