These are from my 3.0 V6 SC Portfolio. 43k miles.
Diagnostically; What does the condition of these valves tell you?
Photos are labeled by cylinder C1, Etc.
Thanks.

 

You haven't told us the mileage of your car, but it looks about right for a fairly high miles car. The YouTuber "The Car Wizard" showed a car far worse than this, and how he cleaned up the valves. Does the engine use GDI (Gasoline Direct Injection) <into the cylinders> ?

 

It's in his sig which maybe you can't see:
x351 ‘14 XJL 3.0 V6 SC RWD 40k
Yep, definitely carbon deposits / build-up due to GDI, and I have seen that particular Car Wizard video as well.
I have twice used this gear on my 3.0 V6 F-Type, also around the same mileage as the OP's XJL:

You Tube

Relatively cheap and fairly easy to use, I even figured out a way to do it on my lonesome.
Of course without major exploratory work I can't tell how well it worked if at all, all I know is the car coughed up lots of grey/black smoke through the exhaust and the insides of the exhaust tips were the blackest they had ever been for a few days until I cleaned them up.

 

I've seen another video test of one of the "spray in" valve cleaners with before and after borescope pictures which showed almost no discernible difference. Having done the cleaning myself manually, I can tell you that stuff is pretty gummy and fairly impervious to even soaking for half an hour in carb cleaner. There's no way a dilute spray through the throttle body is going to do much. Maybe if you did it every 5,000 miles and just never let it get that bad. If you don't have the whole walnut shell media blaster setup, it takes some dental pick action followed by a generous scrubbing with a stiff bottle brush after soaking a few minutes in carb cleaner. Getting access to be able to see inside the rearmost valves is the problem, slightly mitigated in the v6 not having the back two to have to reach but you still need to be like 7 feet tall to lean over that far.

 

Too bad your not running Meth injection. Your valves would be spotless!
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I don't think I'd want to just scrub carbon off of the valve stems without vacuuming it all out and making absolutely sure that there's nothing big & hard left to go into the cylinder (smaller stuff, no problem). These valves might be saying that they'd appreciate an intake cleaning service, be it by yourself or by a professional (BG website can recommend servicers). They could also be saying something about the oil you're using, how often it's being changed, or possibly how clean your air filters are (or at least if they're extremely dirty restricting flow).
That's the thing with direct injection - no fuel flows over the intake valves, so they're at the mercy of the air intake and oil from the EGR or ... other(?).
But the shape of build-up will have at least some impact on the smooth flow of air into the combustion chamber, which can have some (slight, but noticeable if you pay attention) impact on performance. The engine wants to breath well.

 

Those needs a good cleaning. I cleaned mine a year ago with 118k miles, and they didn't look too much worse than yours. I don't think the CRC spray cleaner would do anything if the deposits are already formed but it may help keep them clean after they've been scrubbed manually (or walnut blasted).