window.diff="tab_vsplit" leaves split behind

[bugsbugsbux]

Describe the bug
window.diff="tab_vsplit" also opens a horizontal split with one of the files

To Reproduce

• nvim --clean
• :lua = vim.pack.add{'https://github.com/willothy/flatten.nvim/'}
• :lua require('flatten').setup()
• :term
• have some git conflicts and run git difftool
• opens new tab with the diff in vsplits
• :q and :q
• back to terminal but a horizontal split still shows one of the files

Expected behavior
opens tab with the diff in vsplit windows
does not open a horizontal split

Minimal Init
see above

Desktop (please complete the following information):
archlinux
NVIM v0.12.2 Build type: RelWithDebInfo LuaJIT 2.1.1774896198
terminal: foot version: 1.26.1 +pgo +ime +graphemes +toplevel-tag +blur -assertions
tmux: 3.6a
flatten.nvim: {"rev": "72527798e75b5e34757491947c2cb853ce21dc0e", "src": "https://github.com/willothy/flatten.nvim"}