Version: fish, version 3.3.1
OS: Linux thinkpad-e570 5.12.14-300.fc34.x86_64 #1 SMP Wed Jun 30 18:30:21 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux (Fedora 34 Workstation)
Terminal: xterm-256color (Gnome Terminal)

Today I discovered that fish supports escape sequences like \u2215 and \145.
This can be used inside commands like \145cho Hello World \U0001f41f.
However this leads to weird errors when the input starts with an escape (maybe only invalid ones from what I observe) and fish tries to autocomplete it...

septatrix@thinkpad-e570 ~> \utest  # now press space
septatrix@thinkpad-e570 ~> \utest source: “/home/septatrix/.config/fish/functions/” is not a file
source: “/home/septatrix/.config/fish/completions/” is not a file