Some fontsizes do not render the ligatures properly

[lygamac]

Describe the bug
While in the default fontsize (12pt), and some others, the ligatures do render properly. But for some fontsizes it doesn't (e.g. 9pt, 8pt, 14pt.)

To Reproduce
Steps to reproduce the behavior:

1. Add the following config, or similar:

font_family FiraCode
font_size 9

2. Open the terminal and try the ligatures for |---|--------|-------|-------------|-------------|

Screenshots
12pt:

9pt:

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Might be related to #3772?