There is a mistake in make_rectangle_3points geometry:
It should be
make_rectangle_3points(
make_point(to_real(string_to_array(@lowerleft,',')[0]),to_real(string_to_array(@lowerleft,',')[1])),
make_point(to_real(string_to_array(@upperright,',')[0]),to_real(string_to_array(@lowerleft,',')[1])),
make_point(to_real(string_to_array(@upperright,',')[1]),to_real(string_to_array(@upperright,',')[1])
--> Last line !
Check your rect geometry with geometry generator in symbology of a seperate layer that you can see the selecting rectangle and adapt it to your needs.