Don't know if it is relevant through the trim levels, but my 2008 titanium x diesel with 168k miles has a really clunky  gear lever and noisy action. Through 1st to second is not too bad but when I go across the gate is really noticeable and the worse is when in neutral and waggle it side to side, I can also feel resistance. I lifted the trim and sprayed wd40 which helped a little bit. It looks like the factory grease has chunked up and looks dry. All the connectors for the selector cables look pretty good with hardly any movement both inside the cabin and engine side. I Don't know if this is common(they all sound like that mate🤔)as this is my 1st Mondeo. It is a shame, because inside  is really premium and generally quiet. I just want to get it to that next level of plushness. Please tell me I can just swap out for a new lever/selector mechanism and all will be quiet.

Try a bit of lube on the selector rods on the top of the gearbox (in the engine bay). I did the same as you when it first happened but narrowed it down to the selector rods which squeaks and can feel it on the gear stick. Happened twice in 7 1/2 years that I've owned my car.