Today's upgrade pulled in or upgraded dotnet-sdk-3.1 which outputs the following messages:

[…]
Setting up dotnet-sdk-3.1 (3.1.408-1) ...
This software may collect information about you and your use of the software, and send that to Microsoft.
Please visit http://aka.ms/dotnet-cli-eula for more information.
Welcome to .NET Core!

Learn more about .NET Core: https://aka.ms/dotnet-docs
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli-docs

Telemetry

The .NET Core tools collect usage data in order to help us improve your experience. It is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.

Read more about .NET Core CLI Tools telemetry: https://aka.ms/dotnet-cli-telemetry

Configuring...

A command is running to populate your local package cache to improve restore speed and enable offline access. This command takes up to one minute to complete and only runs once.
Setting up powershell-empire (4.0.0+gitsubmodule-0kali1) ...
[…]

So please add DOTNET_CLI_TELEMETRY_OPTOUT=1 to /etc/environment via the kali-defaults package