Various devices I had attached (PC, XBox Series X, Apple TV) list maximum supported 60 Hz with this TV. However, there is an HDMI 4 output that is supposed to deliver 4K@120 Hz when gaming mode is activated, according to Samsung (https://www.samsung.com/ch/tvs/qled-tv/q90t-55-inch-qled-4k-smart-tv-qe55q90tatxzg/). I have not (yet) been able to reproduce this consciously - the gaming mode goes on and off as it wants, possibly it actually supports 120 Hz as long as it is on, but does not switch to on when only the display settings of the corresponding devices are open.

the QE55Q90T has 3 x HDMI 2.0 and 1 x HDMI 2.1

Countless apps are preinstalled, such as Netflix, Sky, Disney+. Sure, you can install more apps. It has many more gadgets. I am very satisfied with the device.

Plug T 12 CH

A connection cable white with Euro plug angled 2 pole appliance side appliance plug double groove available at Digitec (Hama Netzkabel Doppelnut )

i tested both, samsung qled q90t vs. lg oled cx. since i use it mostly as pc-monitor, i kept the qled, i noticed burn-in on the oled after only a few days, both the browser windows and 4: 3 movies left remains on the oled-panel. the qled is also brighter (important during daytime !) and shows better details in dark areas, i had to turn up the brightness on the oled significantly (black-crush), so you loose the perfect oled-black. digitec offered me to bring back the tv to the shop (zürich), so no postal fee, BUT they only pay you back 90% ! fortunately, i picked up the oled myself from a melectronics-shop (which returns the full prize), and the qled from digitec, so i lost nothing but the time for the transports.

Hello. Your TV has probably automatically set up your PC as a PC. For whatever reason, only the picture styles Dynamic Standard and Game Mode are available as Pc. Press the Home button on the TV to the left on Source, then select your connection from the PC, press Edit at the top and select something else there. Then all picture styles are available again. HDR and 120Hz in all picture styles can only be set on my PC under Windows if I connect it to the HDMI2.1 connection with an 8k HDMI cable and the "Club 3D Adapter DP 1.4 to HDMI 4K120Hz HDR Active Adapter". (The TV activates HDR automatically as soon as it is set on the PC). Via HDMI2.0, I can only use 60hz at 4k on my PC. Exceptions: In gaming mode up to 4k and with the other picture styles in FullHd resolution, up to120hz is also possible via HDMI2.0. But no HDR. Greetings

My understanding is that it is 60 Hz in normal mode, 120 Hz in game mode, which is however only available for one of the ports.

No, up to 120Hz, see https://www.displayspecifications.com/en/model/8b1e1e1b

No, it is the displayed price minus the promotional code of 10% 'JAN21'. Until 03.02.2021