HTTP encoding does something strange.

I'm connecting my flic to a tasmota shelly 1 REST api with the following request.

http://<ip>/cm?cmnd=Backlog%20Power%20On%3BDelay%2010%3BPower%20off

But on the receiver side the request looks like this:

http://<ip>/cm?cmnd=Backlog%20Power%20On;Delay%2010;Power%20off

The %3B (;) encoding is lost, which defeats the purpose of encoding it in the first place I guess ...
Sadly the tasmota software cannot handle ; only the encoded value %3B.

%20 is not being decoded before sending the request, as should none of the other enoded values IMHO.