I don't see anything I would describe as "pixelized". Rather, it looks more like a rendering problem. I have tested this on the Google Fonts site, and with a simple HTML document, both viewed in Firefox and Chrome (Windows 10), with text at the same size, and rendering looks identical to me.
However I have noticed that the "a" doesn't render so well at some font sizes.
At 36px, the upper storey curve of the "a" is thickened. Whereas at 35px it looks much better. As to the source of the problem, I'm not sure. Perhaps it's a Win10 issue, a browser rendering problem, or perhaps the font design itself.
Here's the HTML if anyone wants to test it:
<link rel="preconnect" href="https://fonts.gstatic.com">
<link href="https://fonts.googleapis.com/css2?family=Merriweather:wght@400;700&display=swap" rel="stylesheet">
<h1 style="font-family: 'Merriweather', serif; font-size: 36px; font-weight: 700;">Leader election in Go</h1>
<h1 style="font-family: 'Merriweather', serif; font-size: 35px; font-weight: 700;">Leader election in Go</h1>