Three volts only

Nothing in between

Five of the eight pins go straight from the header to the panel's ribbon. There is no resistor, no level shifter and no regulator on the way. So the voltages your board puts on them are the voltages the controller gets.

The controller is a Sitronix ST7735S. Its data sheet runs its logic from 1.65 to 3.7 V, and here that supply is the board's 3V3. It reads anything over 0.7 of that, 2.31 V, as HIGH. And it allows no input to go more than 0.3 V over its supply: 3.6 V.

An ESP32, an ESP32-S3 and a Raspberry Pi Pico all drive their pins at 3.3 V: a clean HIGH, under the limit. They wire straight across, 3V3 to 3V3.

An Uno needs a TK97

An Arduino Uno drives its pins to 5 V. That is 1.4 V past the limit on every HIGH, and SCL alone goes HIGH millions of times a second. The back of the board says it in a box: use it with 3.3 V boards, and put a TK97 logic level converter between it and a 5 V Uno, to prevent damage, flickering or blurring.

In the owner's diagram the TK89 plugs straight into the socket on the TK97's 3.3 V side, marked GND, 3V3 and L1 to L6. The Uno sends 5V, GND and its six signals into the other side.

Two things come with the converter. It rounds the edges of a fast clock, so if the picture is noisy through it, slow the SPI clock. And it is one more thing to wire wrongly: when an Uno build shows nothing, check the TK97's 5V and GND wires first.