Changing background color in Red doesn't work in Neovim

[mattthhh]

Environment

• Output of nvim --version:

Using neovim :

NVIM v0.8.0
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3
Compilation: /usr/bin/cc -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -Wp,-U_FORTIFY_SOURCE -Wp,-D_FORTIFY_SOURCE=1 -DNVIM_TS_HAS_SET_MATCH_LIMIT -DNVIM_TS_HAS_SET_ALLOCATOR -O2 -g -Og -g -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wdouble-promotion -Wmissing-noreturn -Wmissing-format-attribute -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -DMIN_LOG_LEVEL=3 -I/builddir/build/BUILD/neovim-0.8.0/x86_64-redhat-linux-gnu/cmake.config -I/builddir/build/BUILD/neovim-0.8.0/src -I/usr/include -I/usr/include/luajit-2.1 -I/builddir/build/BUILD/neovim-0.8.0/x86_64-redhat-linux-gnu/src/nvim/auto -I/builddir/build/BUILD/neovim-0.8.0/x86_64-redhat-linux-gnu/include
Compiled by mockbuild@koji

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/share/nvim"

Run :checkhealth for more info

• Platform:

  • [X] Linux
  • [ ] Mac OS X
  • [ ] Windows

• :checkhealth floaterm :

  floaterm: require("floaterm.health").check()
  ========================================================================
  - ERROR: Failed to run healthcheck for "floaterm" plugin. Exception:
  function health#check, line 20
  Vim(eval):E5108: Error executing lua .../vim-floaterm/start/vim-floaterm/lua/floaterm/health.lua:24: attempt to call field 'start' (a nil value)
  stack traceback:
  .../vim-floaterm/start/vim-floaterm/lua/floaterm/health.lua:24: in function 'check_common'
  .../vim-floaterm/start/vim-floaterm/lua/floaterm/health.lua:55: in function 'check'
  [string "luaeval()"]:1: in main chunk

Bug

When I set the highlight group for guibg for Floaterm as this :

vim.api.nvim_set_hl(0, 'Floaterm', { bg = "red" })

Even if my $TERM is xterm-256color this is the result :

Screenshot

Any ideas ?