Inconsistent glyph height in font rendering in Firefox and Chrome

I noticed that on some web pages the font character vertical positions are inconsistent.

This is an example from spiegel.de/impressum/ with their custom font ‘SpiegelSerifUI’. In this case the lowercase ‘s’ character is going beneath the baseline; almost as if it was a descender character (like ‘g’).

  • Firefox:
    grafik

  • Chrome:
    grafik

A more severe case is the rendering of the ‘P052’ font on djangoproject.com. For this example, I only have a screenshot from Firefox because Chrome uses the ‘Caladea’ font for reasons unknown to me. As you can see from the word ‘mechanism’, the x-height of the characters ‘m’ and ‘n’ differs from the others. In LibreOffice, however, the same font looks just fine.

  • Firefox (P052 font):
    grafik

Do you have the same issue on the mentioned websites? What can I do to fix this issue?