I was going to say this was the second report of this problem in a week - but then realised both support threads were from the same person.
In any case, sprintf() comes from stdio.h, and if you have configUSE_STATS_FORMATTING_FUNCTIONS defined, that is included here: https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/V10.3.1-kernel-only/tasks.c#L56 - so this does appear to be a quirk of your build rather than a FreeRTOS issue.