I can confirm this change in behaviour on the Xperia X. I wasn’t sure at first, but I checked the battery usage graphs in SysMon, and the battery is visibly going down much faster with WiFi enabled on 4.1.0 than it was on 4.0.1. In both cases, no applications or only the camera are/were running, and the only user-intended active online connection is two email accounts with their synchronisation set to ‘always up-to-date’. Android app support is active, but there are no Android applications running in the background. Hopefully we can find some more similarities and differences between our setups this way to estimate where the problem is actually located.
With WiFi disabled, power consumption appears to be the same as before.
Out of the devices I checked (Jolla C, Jolla Tablet and Xperia X), only the Xperia X has a much larger power consumption on WiFi in comparison to 4.0.1. The Xperia 10 II also seems to have a large power consumption on WiFi, but of course I can’t compare that one with a previous OS version.