Same here. MQTT does not work at all after updating to 20220613-073803/v2.1.6@166b8318 firmware. Same behavior on both of my Shelly Motion devices.
MQTT was working fine with out-of-the-box firmware but I didn't make a note of the version number 
I've reset both of my devices and am using the Shelly integration in Home Assistant instead of MQTT for now.
How did you downgrade?
How did you downgrade?
Grab the firmware from here: https://shelly-forum.com/index.php?shelly-firmware-archive/. Then you just need to use curl or something with your credentials to push the update to your device. Here's an example with httpie. You just need to set your variables for USER/PASS/ADDR respective of your setup.
$ http --auth $USER:$PASS http://$ADDR/ota\?url\=http://archive.shelly-forum.com/v2.0.5/SHMOS-01_build.zip
HTTP/1.0 200 OK
Content-Type: application/json
Server: lwIP/2.1.2 (http://savannah.nongnu.org/projects/lwip)
{
"has_update": false,
"new_version": null,
"old_version": "20220613-073803/v2.1.6@166b8318",
"status": "updating"
}The issue has been forwarded directly to the Allterco developers.
Please be patient now.
Thanks.
