[Bug]: Small vertical line before powerline and box drawing characters in Nerd Fonts

Checklist

• I have read the appropriate section in the contributing guidelines
• I believe this issue is a problem with polybar itself and not a misconfiguration on my part
• I have searched for other open and closed issues that may have already reported this problem
• I have checked the known issues page for this problem.
• I have followed the debugging guide to narrow down the problem to a minimal config.

Steps to reproduce

polybar -c config.ini main

Minimal config

[bar/main]
font-0 = "Literation Mono Nerd Font:size=22"
modules-left = mod1 mod2
background = #ffffff
foreground = #000000

width = 100

[module/mod1]
type = custom/text
label = " %{+u}█%{+u}█%{+u}█"

[module/mod2]
type = custom/text
label = █
label-foreground = #dddddd
label-background = #000000

Polybar log

notice: Parsing config file: config.ini
notice: Loading module 'mod1' of type 'custom/text'
notice: Loading module 'mod2' of type 'custom/text'
notice: Loaded 2 modules
notice: Loaded font "Literation Mono Nerd Font:size=22" (name=LiterationMono Nerd Font, offset=0, file=/usr/share/fonts/TTF/Literation Mono Nerd Font Complete.ttf)

Expected behavior

All the characters should be flush without a gap in between.

Actual behavior

There is a 1px red-ish gap before the box-drawing character with black foregound and a blue-ish gap before the box-drawing character with a gray foreground.

Window Manager and Version

HerbstluftWM 0.9.5

Linux Distribution

ArchLinux

Polybar version

polybar 3.6.3-80-g30e1cc25

Features: +alsa +curl +i3 +mpd +network(libnl) +pulseaudio +xkeyboard

X extensions: +randr (+monitors) +composite +xkb +xrm +xcursor

Build type: Release
Compiler: /usr/bin/c++
Compiler flags: -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions         -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security         -fstack-clash-protection -fcf-protection -Wp,-D_GLIBCXX_ASSERTIONS -flto=auto -O3 -DNDEBUG -Wall -Wextra -Wpedantic -Wdeprecated-copy-dtor -Wsuggest-override
Linker flags: -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -flto=auto -Wall -Wextra -Wpedantic -Wdeprecated-copy-dtor -Wsuggest-override  -Wall -Wextra -Wpedantic -Wdeprecated-copy-dtor -Wsuggest-override

Additional Context / Screenshots

I initially thought this was the same issue as #2785, but the fix for that issue does nothing here.

This only happening when there is a tag in between is a strong indication of a similar underlying problem though.