Ah, turns out there was some write to the UART in another of the code that I was unaware. A single character really does transmit as advertised in 10 characters.

Sorry for any inconvenience.

I am connecting an ESP32 with a FPGA (Digilent Cmod A7). The data transfer will be bi-directional using the UART at 115200. The ESP32 is sending a single byte to the Cmod A7 using a Serial2.write(val). Where val == 'a' (ie 10101010). I am writing the FPGA driver to send and receive data from the ESP...