how to fix two chat windows in skype for business ltsc 2021?

Question

child item tag show skype for business linㅕx only...

This is question for Windows SFB.

1.

I use MS office ltsc 2021 included skype for business and dual monitor

I have a chat with someone and move a chat windows to second monitor, show two same chat windows in taskbar.

also close that chat window, stay one window until shut down SFB.

did you see this bug? and where can I get bug fix about this?

2.

Why doesn't save conversation history larger than 1mb? from lync 2013 until now?