How does task scheduling affect peripheral timing?

I have UART code that works. However, said UART code does not work inside a task and instead I get output that looks like the baud rate is wrong. I was therefore wondering how the FreeRTOS scheduler affects the timing for peripherals for embedded devices (sorry if this is the wrong topic section, wasn’t sure as my inquiry is more general theory to understand my problem better). It does use an interrupt, so that would be my next guess and next question on how FreeRTOS affects interrupt handling, whether the interrupts have an ISR attached or not. I know there are ISR specific task functions, so I am curious about this also. Many thanks in advance.

Which hardware and FreeRTOS port are you using? Is the driver you are using RTOS aware?

FreeRTOS does not do anything to the peripherals.

FreeRTOS disables interrupts for very short critical sections but it should not produce the results you are seeing.

If you want to handle an interrupt, you need to install the corresponding ISR. How that is done, depends on the hardware and FreeRTOS is not involved in that.