I am close to dismantle all sonoff devices due to that issue. D1 dimmers sometimes works sometimes not. group dimming is not working well, the device is too big to fit it into the box with other cables and can't work with any standard switch. PIR sensors gives fake alarms, bridge disconnects quite frequently from wifi beside it is located 2m away from router...
I experienced the same as Jose Pro.
But my PIR sensor only stopped giving false alarms when I removed a metal grid mounted just in front of it!
I think there was a warning in the user guide against metal in front of the PIR sensor.
I have no metal parts in front except the metal casing near the floor where valves from my floor heating are hidden. Actually I don't think its the case because completely two separate PIR sensors triggers at exactly the same moment (one outside the house, one inside), minute and even second which is technically impossible. It is rather a software bug in the bridge or... I don't know interference or noise from something that both PIR sensors detects as movement at the same moment. I would probably give up to something else and sell all sonoff devices.