Question about Dell UltraSharp U3818DW

I have this combo. The notebook is supplied with enough power, including charging the battery, and the screen is controlled at full resolution.
Ingenious for office and photo, both too slow for gaming.
Just after the last update, the monitor was only recognised with a mirrored image during the automatic "warm start" of the notebook (otherwise extended desktop is possible). Power-down, unplug the monitor cable (USB-C/Thunderbolt) helps. Boot the MacBook, plug in the monitor when logged in, and everything is fine again.
Since the additional graphics card in the MBPro often has a lot to do, depending on the task, the Venti in the MBPro tends to start up. A notebook stand that allows better ventilation is helpful 😉.