[NAME]  The TB16 with a 240W power supply can only supply 130W to the attached system, as opposed to the TB16 180W that only provided 90W to the attached system.  Because the 130W system output was insufficient for Precision 7000 Series systems, Dell's guidance for the TB16 was that when using it with Precision 7000 systems of that era, including your Precision 7510, users should keep the system's own power adapter directly connected as well. If your system never complained about a low wattage power source, it's because your system had its adapter warnings disabled, which you can do by disabling that in the BIOS (and can trigger by pressing a hotkey whenever you see a warning, so it could have been done inadvertently).  Starting with the Precision 7x30 systems, Dell began adding two USB-C/TB3 ports to its systems and also released the TB18DC, which plugged into BOTH of those ports and consequently was able to provide up to 210W of power to the attached system, enough to run Precision 7000 Series systems optimally without needing a separate power supply connection.  The TB18DC has since been replaced by the WD19DC and then the WD19DCS.So you haven't been downgraded.  You're just seeing an error that was suppressed on your previous system, and you've been upgraded in the sense that you now have a system that is capable of being powered optimally purely from a dock, without needing auxiliary power.  That option wasn't even available on the 7510 -- but it does require a different dock than you currently have.
I've been using a Dell Precision 7510 for work with a TB16 dock that was recently replaced with a Precision 7560.  My TB16 dock had a 240W power supply for it to power the 7510. When I plug in the 7560 into the TB16 via the USBC it says that it is charging but it isn't optimal. Since the old laptop worked without any issue and the power supply on the TB16 is more than adequate, as well as a higher wattage than the power cable that came with the 7560, why doesn't the TB16 generate the necessary power for the 7560?  From what I've found in reading it looks like there is a newer TB model that seems more compatible with the 7560, is this more of a case of planned obsoleteness for the TB16 for the new laptop or is just not fully compatible with the 7560?
Precision 7560 and TB16