ddr4 trace width in altium sodimm example

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Hello everyone
in examples of mini pc altium there is a pcb that its name is sodimm ddr4 . my question is that as you see in pic2 the width of trace is 0.15 mm and before it arrives to ddr4 the width changes to 0.075mm and route flyby topology across the ddr4s (pic3) . and he could rout all of tracks 0.15mm or 0.075mm .do you understand why?
the pcb is in examples of altium.

[robertferanec]

I can't see the track width changed in the full layout, where exactly it is on the last picture?

The track width can by sometimes changed to accommodate impedance due additional capacitance of input pins. Eric mentioned it in one of my interviews, I think it was in thisone: https://youtu.be/U60y4JC0Wxs

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in this picture the trace width changes...

[robertferanec]

but where is this place on the last picture?

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i uploaded the pcb in the zip file and marked the place with red rectangle in the picture