Yes, recent memory optimizations broke concentric infill too

lib/Slic3r/Fill/Concentric.pm

@@ -53,6 +53,7 @@ sub fill_surface {
     );
     foreach my $loop (map Slic3r::ExtrusionLoop->new(polygon => $_, role => EXTR_ROLE_FILL), @loops) {
         # extrude all loops ccw
+        $loop->deserialize;
         $loop->polygon->make_counter_clockwise;
         
         # find the point of the loop that is closest to the current extruder position
@@ -60,6 +61,7 @@ sub fill_surface {
         
         # split the loop at the starting point and make a path
         my $path = $loop->split_at($cur_pos);
+        $path->deserialize;
         
         # clip the path to avoid the extruder to get exactly on the first point of the loop
         $path->clip_end(scale $Slic3r::flow_width * 0.15);