The increase in the resistivity with decreasing temperature followed by a drop by more than one order of magnitude is observed on the metallic side near the zero-magnetic-field metal-insulator transition in a strongly interacting two-dimensional electron system in ultra-clean SiGe/Si/SiGe quantum wells. We find that the temperature $T_{text{max}}$, at which the resistivity exhibits a maximum, is close to the renormalized Fermi temperature, in agreement with the dynamical mean-field theory. However, rather than increasing along with the Fermi temperature, the value $T_{text{max}}$ decreases appreciably for spinless electrons in spin-polarizing magnetic fields, which is in contradiction with the theory in its current form. Remarkably, the characteristic scaling of the resistivity, predicted by the theory, holds in both spin-unpolarized and completely spin-polarized systems.
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