SAI has no "TDM mode", so the following instances in SAI chapter of RM should be rephrased, possibly to "Free protocol is selected (SAIxy_CR1.PRTCFG = 0)".
These instances can be found easily by textual search for "TDM".
This of course is not 'F446-specific; I assume whoever will make changes in docs will do it for all related STM32 models.
I use SAIxy_CR1 instead of the official SAI_ACR1 / SAI_BCR1, as it's confusing and won't match the style in other IPs' chapters nor the registers names in the CMSIS-mandated headers. I don't say my style is better.