I have noticed that sometimes I obsess on the articulations on some of the pillars of Salah (like Al-Fatihah and the taslīm), I feel that sometimes I missed the articulation of the letter lām in the taslīm. And reciting Fatihah feels heavy only during the fard Salah. any advice on overcoming this?

Ustadh AbdulAziz al-Haqqan

This is waswas, so ignore the thought and say what you are able to without burdening yourself, your salah is valid. Do not repeat and do not keep asking about it, because asking is what feeds it.