Is it obligatory to wait for congregational prayer in a mosque that delays the prayer without a valid excuse until just before Asr, or is it better to pray at home at the beginning of the time?

The preponderant view is that congregational prayer is an individual obligation (fard ayn). This is supported by the hadith: "Whoever hears the call [to prayer] and does not come, there is no prayer for him except for one with an excuse." Therefore, it is not permissible to abandon the congregation, even if the imam delays the prayer until near the end of its time, because as long as it is within its prescribed time, it is valid and suffices. It is obligatory to maintain congregational prayer and to advise the mosque community that it is preferable to perform the Dhuhr prayer early, except in cases of intense heat. If another mosque is found that adheres to the Sunnah, or another congregation that prays at the beginning of the time, then it is better to pray with them.