Is it permissible for the Imam to delay the Dhuhr prayer until the end of its time and to offer the Asr prayer at the beginning of its time with the intention of a suwari (formal) combining, and should we pray with him or in another mosque?

The time for Dhuhr prayer begins when the sun declines from the meridian and extends until the shadow of everything becomes equal to its height. If the congregation performs the Dhuhr prayer ten minutes before the time for Asr prayer begins, this means it was prayed within its prescribed time, and there is no sin upon them, even if they missed the virtue of praying it early. It is recommended to pray Dhuhr at the beginning of its time, except during intense heat, in which case it is recommended to delay it, based on the hadith: "When the heat becomes intense, cool down by delaying the prayer." It is also authentically reported that the Prophet (peace be upon him) delayed Dhuhr and hastened Asr. In summary: there is no need to avoid the mosque as long as the optional time for prayer has not expired.