How to view the quota limits of an APFS volume that I had set at the time of its creation?
Yes you can with the terminal command :
diskutil ap list diskX

where diskX is to be replaced by the Container &quot;Time Machine&quot; identifier
On my Mac i get this :
    diskutil ap list disk4              
|
+-- Container disk4 8C53B410-FC36-4221-9F13-F528C24CA4EC
    ====================================================
    APFS Container Reference:     disk4
    Size (Capacity Ceiling):      80134217728 B (80.1 GB)
    Capacity In Use By Volumes:   7213264896 B (7.2 GB) (9.0% used)
    Capacity Not Allocated:       72920952832 B (72.9 GB) (91.0% free)
    |
    +-&lt; Physical Store disk3s6 D6E20B9A-34FF-462E-8AEE-5648523C1E5D
    |   -----------------------------------------------------------
    |   APFS Physical Store Disk:   disk3s6
    |   Size:                       80134217728 B (80.1 GB)
    |
    +-&gt; Volume disk4s1 8E6FC6CF-149A-4A8C-BD4E-228953A8C07F
        ---------------------------------------------------
        APFS Volume Disk (Role):   disk4s1 (Backup)
        Name:                      Time_Machine_BS (Case-sensitive)
        Mount Point:               /Volumes/Time_Machine_BS
        Capacity Consumed:         7091273728 B (7.1 GB)
        Capacity Reserve:          None
        Capacity Quota:            20000002048 B (20.0 GB) (35.5% reached)
        FileVault:                 No