GParted 1.8.0 [1] has just been released which includes a fix for this issue [2].
[1] GParted 1.8.0
https://gparted.org/news.php?item=260
https://gitlab.gnome.org/GNOME/gparted/-/blob/GPARTED_1_8_0/NEWS?ref_type=tags#L25
[2] Create mount points in a private temporary working directory
https://gitlab.gnome.org/GNOME/gparted/-/merge_requests/139
Thanks,
Mike Fleetwood (GParted Developer)

