closePane vs. closeTab differences?

Environment

Windows build number: 10.0.18362.592
Windows Terminal version (if applicable): 0.8.10261.0

Any other software?
WSL 2 (Debian 10)
bash 5.0.3
OpenSSH_7.9p1 Debian-10+deb10u1, OpenSSL 1.1.1c

Not entirely sure where this lies, but starting here since I can't recreate it elsewhere (putty, cmd.exe)

When closing a WSL session by either middle mouse clicking the tab (NOT the X) or by running the "closeTab" command via a hotkey, my ssh session will terminate and the application that's running receives a SIGHUP.

When closing a WSL session by clicking the X on a tab or by running the "closePane" command via a hotkey, my ssh session will terminate and the application that's running receives both SIGUSR1 (first) and SIGHUP.

This isn't an issue per se, but I'm trying to track down a bug in our own application and part of it seems to be related to how the application was terminated. Our end users don't use Windows Terminal, but in trying to understand how to create this scenario I've been working through different SSH clients.

What does Windows Terminal do differently when closing a tab using "closePane" versus "closeTab"?

Reproduce the behavior in the stated Windows Terminal, WSL 2 Debian, bash, and OpenSSH environment using middle-click, the closeTab hotkey, the tab X, and the closePane hotkey. Compare the resulting signal sequences and determine whether the distinction is intentional; done should document the difference or identify a reproducible terminal bug.