alacritty: Can't make new undercurl pretty as xfce4-terminal

The newly implemented undercurl doesn’t look like undercurl at all on my setup. Curiously, the same setup, just changing to xfce4-terminal, look as expected (xfce4-terminal vs Alacritty):

System

OS: Arch Linux Version: alacritty 0.11.0-dev (4734b2b8) Linux: X11, i3

Logs

Font/Terminal size:

[0.000000983s] [INFO ] [alacritty] Welcome to Alacritty
[0.000051009s] [INFO ] [alacritty] Version 0.11.0-dev (4734b2b8)
[0.000073608s] [INFO ] [alacritty] Running on X11
[0.002359693s] [INFO ] [alacritty] Configuration files loaded from:
                                     "/home/francisco/.config/alacritty/alacritty.yml"
[0.005135142s] [DEBUG] [alacritty] Loading "Terminus" font
[0.016950699s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Regular, load_flags: MONOCHROME | TARGET_MONO, render_mode: "Mono", lcd_filter: 1 }
[0.020442538s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Bold, load_flags: MONOCHROME | TARGET_MONO, render_mode: "Mono", lcd_filter: 1 }
[0.023641749s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Italic, load_flags: TARGET_LIGHT, render_mode: "Normal", lcd_filter: 1 }
[0.026568008s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Bold Italic, load_flags: TARGET_LIGHT, render_mode: "Normal", lcd_filter: 1 }
[0.027802135s] [DEBUG] [alacritty] Estimated scaling factor: 1
[0.027810002s] [DEBUG] [alacritty] Estimated window size: None
[0.027814010s] [DEBUG] [alacritty] Estimated cell size: 8 x 14
[0.176838897s] [INFO ] [alacritty] Display scale factor: 1
[0.176856938s] [DEBUG] [alacritty] Filling glyph cache with common glyphs
[0.178775852s] [INFO ] [alacritty] Cell size: 8 x 14
[0.178787146s] [INFO ] [alacritty] Padding: 0 x 0
[0.178790883s] [INFO ] [alacritty] Width: 800, Height: 600
[0.186151579s] [INFO ] [alacritty] PTY dimensions: 42 x 100
[0.188512976s] [INFO ] [alacritty] Initialisation complete
[0.204555657s] [DEBUG] [alacritty_terminal] New num_cols is 116 and num_lines is 74
[0.220608513s] [INFO ] [alacritty] Padding: 0 x 0
[0.220628922s] [INFO ] [alacritty] Width: 929, Height: 1040
[0.281550163s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Bold, load_flags: TARGET_LIGHT, render_mode: "Normal", lcd_filter: 1 }
[0.281790726s] [DEBUG] [crossfont] Loaded Face Face { ft_face: Font Face: Bold, load_flags: TARGET_LIGHT, render_mode: "Normal", lcd_filter: 1 }

Note, the Terminus font I use has a personal fontconfig configuration.