Hello erdemcanturk,
Welcome to Apple Support Communities.
We understand that you’re getting an error when trying to access your lights from the Home app. We are happy to help.
Many times restarting your devices can resolve many concerns. Please use the steps here to restart your Apple Watch: Restart your Apple Watch - Apple Support
"How to restart your Apple Watch if you have watchOS 9
- If your Apple Watch is charging, take it off the charger.
- Press and hold the side button until you see the power button in the upper-right corner of the display.
- Tap the power button.
- Drag the Power Off slider.
- After your watch turns off, press and hold the side button again until you see the Apple logo."
We also recommend using the steps here to restart your iPhone: Restart your iPhone - Apple Support
"How to restart your iPhone X, 11, 12, 13, or later
- Press and hold either volume button and the side button until the power-off slider appears.
- Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo."
We also recommend updating the apps on your Apple Watch. Go to the App Store app on your Apple Watch and got to Account and Tap on Updates to see if there are any updates available.
Let us know if you have further questions.
Take care.