Do you have the SWDIO connected? I see that use ~300 uA. Just this evening I ‘ported’ my RAK3172 sample repo to the RAK3172-SiP, which made it easy to measure sleep current of only the STM32WL + TCXO in isolation (excluding LDO current use, Vbatt divider current. etc).
With this I’m seeing under 2uA sleep current. I did have to tinker with the ADC configuration, I found it was consuming ~3mA unexpectedly, I have not root-caused that yet. It’s possible you have a peripheral that’s in a power-hungry state like this.
You might have a look at the ST errata list for the STM32WL, I will myself in the morning.
@beegee after the weekend, I should be publishing a branch of my repo with these changes. Overall, very little change needed, just the changed GPIOs for RF switch and configure RCC to use the TCXO.