Please find below a short list of things to check when targeting low current consumption when the Wi-Fi power save mode is enabled:
1) The LP_CLK (32.768KHz +/-1000ppm) has to be provided (not useful if you don't care about current consumption).
2) The frequency drift of LP_CLK within 1 second should be lower than +/-100ppm.
3) The WUP signal should be connected between the host and the WF(M)200.
4) The WUP and WIRQ management should be carefully done to optimize the current consumption (see the source code of WFX driver examples provided on Github).
5) The SPI or SDIO clock should be the highest (respectively 42MHz and 50MHz) to reduce data and management transfer time between the host and the WF(M)200.
6) The resistor pull-up on SDIO interface could increase the current consumption (should be in the host according to the SDIO standard).
7) The WF(M)200 GPIOs usage like FEM or PTA will add additional current consumption on WF(M)200.
8) All pull-up/pull-down resistors on used WF(M)200 GPIOs could impact greatly the average current consumption.
9) Power limitation in Tx or backoff usage could reduce the current consumption in TX (but this also reduces the coverage).
10) VDD_RF, VDD_D, VDD_IO could use 1.8V to reduce power consumption (or 3.3V) but VDD_PA uses only 3.3V nominal (see WF200 or WFM200 datasheet operating conditions).
VDD_IO could be only set to 1.8V If the SPI or SDIO host interface support 1.8V (check also this for other signals like WUP/WIRQ...).
Off course these previous items are some basics and the customer should take care to the host consumption and data traffic usage.
To reduce power consumption, it is recommended to use short high bit rate time slot for transmission or reception and then to be without data traffic during as long time duration as possible.
The AN1219 provides some additional details about this (see https://www.silabs.com/documents/public/application-notes/an1219-power-consumption-wfm200.pdf).
See also https://www.silabs.com/community/wireless/wi-fi/knowledge-base.entry.html/2019/03/05/kba_wfx200_dtim3-tmpo and https://www.silabs.com/community/wireless/wi-fi/knowledge-base.entry.html/2019/03/19/kba_how_to_do_curr-U9le