I was assuming that the white-circled numbers under the bass parts were the thoroughbass and that the black-circled numbers above were the scale degrees ...
You are right, this is not the case.
I guess : The numbers are relating to the moveable do (DOREMI= 123).
The excerpt begins in Gm:
G,A,Bb,C,D = 12345
l.h. G =1, r.h. D =5
in the second line (2nd bar) we are in Bb: Bb=Do=1
r.h. Bb,C,D, = 1,2,3, l.h. Eb=4 and E = #4
the black-circled numbers are above the melody (and not the r.h. - I can’t write here on my tab and still see the whole display).
The white-circled are ”solfegging” (doremi) the bass-line.