What should one do if they feel intense fear and an increased heart rate upon entering the mosque for congregational prayer, and this sometimes leads them to withdraw from the row and rarely pray Friday prayer?

It is not permissible to miss Jumu'ah prayer without a legitimate Shar'i excuse. Abandoning it negligently three times causes Allah to seal the heart of the one who leaves it. Performing the prayer in congregation and in the mosque is obligatory according to many scholars. The heart palpitations you feel have no relation to attending the mosque, and they may be from the whispers of Satan. Be diligent in performing Jumu'ah and congregational prayers in the mosque, seek Allah's help, and persist in reciting adhkar. You can also consult a doctor, as it might be an organic or psychological illness.