@Wayne-TP I'm not sure.  I MAY have done that.  I have a lot of Tapo devices...DECO router, plugs, cameras, switches, etc.....but had never used the sensors, so this is my first experience with the Tapo hub. Amazon reviews indicated that it worked with Alexa routines, but after installing it, I found out that it didn't.  Then I found the article on it being Matter compatible which WOULD allow it to work with routines. I don't remember how I added Matter, but I didn't know you could do that within the Tapo app (there was no mention of that in the instructions) so I think I installed it as a Matter device under Alexa.  Installation/Matter needs some better instructions in this area.

Routines have been a little hokey here lately since Amazon installed Alexa+ on my phone.  One of my C120 cameras in the shop would turn ON the lights with motion, but wouldn't turn them off with "no motion" after a specific time.  An identical setup in the garage worked just fine. Finally just power cycled the camera and it seems to work now.  Strange that if I look at routine activity in the Alexa app for the two cams, it shows me activity for the "turn on" routine for both cams, but gives me a "Routine Activity Not Available" for the "turn off" routines, although they both work.  

The temperature sensor worked perfectly to trigger routines to turn my Dreo heater on and off, then it wouldn't....still haven't figured out why.  Still working on it. May try deleting the routines and recreating them.

I am waiting patiently (well, mostly) for the Tapo T150 Presence Sensor.  I am using a motion sensor in the bedroom/bath to turn on the lights and turn them off after 20 minutes.  My wife is unhappy when the lights suddenly go out while she is putting on her makeup!  LOL! There are other sensors available, but I try to minimize the number of apps I have to deal with.  Don't suppose you would want to send me one to try?

  @Crosscut Spent all day trying to get the temp/humidity sensor to work with a routine.  Been through all the hub/sensor installationns several times.  The motion sensors work and trigger my routines just fine, but not the temp/humidity sensor.  It works just fine if I test the routine in the Alexa app, but apparently the temp sensor will not trigger a routine on temperature change.  

I finally gave up on that and created a smart automation to send me a notification when the temp drops below 71 degrees and when it rises above 73 degrees.  It sends a notification to messages in the Tapo app and gives me a popup, but no push to system notifications.  If that had worked, I could use Macrodroid and VirtualHome to trigger on the notification text. All notification parameters are set to on in the Tapo app and system settings.  

I need a way to turn my heater off and on with an external sensor.  May have to look elsewhere.    

  @Wayne-TP  I gave up on using the temp sensor in a routine.  It's just too unreliable.  As you know, unlike a thermostat, a sensor will trigger on change, so if you are shutting down a heater when a specific temperature is reached and it doesn't trigger, it will continue to heat until you shut it down manually.  Personally I think EVERY heating cooling device should support an external thermostat. 

I finally got the temp sensor to push notifications after trying every setting I could think of.  Setting the Tapo app to have unrestricted power usage in background seemed to be the fix.  I tried that for a while and it consistently pushed notifications when a temp setting was reached. I set up an automation to include the temp value in the notification. I used VirtualHome to set up two "doorbells" for Alexa to turn on my heater on and off in a routine.  I then setup Macrodroid to trigger a macro  on notifications from the Tapo app with the temp limit values in the notifications.  That has been very reliable for the last couple of days.

Then....

I had purchased a door sensor to tell me when my shop door was open.  Yesterday I tried installing that.  Since it was in the shop, I had to move the sensor hub because it was too far away.  After I plugged the sensor hub back in, I now have multiple sensor devices in the Alexa app again.  There are a number of posts on Reddit and other forums about other users having this problem.  Fortunately, summer is not far away.  Hopefully by next year, Tapo will fix this hub/sensor problem.  I'm tired of working on it. If not, will dump the whole sensor setup and try something else.

I hate hubs and try to avoid them at all costs.  They vastly complicate smart home setups.  

less because I now to to have a hub close enough to the devices it supports.  

  @Wayne-TP 

I have been through Tapo Support a several times in the past.  Working with them is like mating elephants.   It's accomplished with a lot of roaring and screaming and takes two years to produce results.  You have to fight your way through multiple levels and the levels don't communicate with each other which means every time you get a different technician, you have to describe the issue several times, send screenshots, pictures, etc. all over again until you finally get to someone who will actually look at the problem.

I will contact them, but only in a minimal basis.  I'm sure they are aware of the problem.  If not, they should be.  It's an easy to find thread in a number of forums and in a Google search. Search  "Alexa creates multiple devices for Tapo sensors".