There is no question, given the prophetic traditions (below) on the subject, that it is wajib (obligatory) to pray all congregational prayers (including the jumu’ah prayer) with no gaps between those those who make up the congregational prayer lines. The Prophet (ﷺ) said:
سَوُّوا صُفُوفَكُمْ فَإِنَّ تَسْوِيَةَ الصُّفُوفِ مِنْ إِقَامَةِ الصَّلاَةِ
“Straighten your rows as the straightening of rows is part of the establishment of salah.”
Also, it was narrated that Al-Bara bin Azib said:
“The Messenger of Allah (ﷺ) used to go between the rows from one side to another, patting our shoulders and chests and saying: ‘Do not make your rows ragged or your hearts will be filled with enmity toward one another.’ And he used to say: ‘Allah and His angels send Salah upon the front rows.”‘
Also, Jabir b. Samurah reported the Messenger of Allah (ﷺ) as saying:
“Why do you not stand in rows as the angels do in the presence of their Lord? We asked: how do the angles stand in rows in the presence of their Lord? He replied: they make the first row complete and keep close together in the row.
If that which is wajib (obligatory) in the congregational prayer has been made unimplementable/impracticable (for any reason) on all those making up the congregational prayer, such congregational prayer becomes batil (invalid).
When encountering the imposition of distancing in a congregational prayer, the believer must pray it individually, to ensure that the prescribed prayer is sahiha (valid/sound), or he can join a congregational prayer (wherever that may be) which is not subject to distancing between those making up the congregational prayer.
If the congregational prayer upon which distancing is imposed happens to be the jumu’ah prayer, such jumu’ah prayer also becomes batil. Therefore, the believer must pray the dhuhur prayer (individually) instead (wherever that may be).
And Allah knows best…