@Christian1985 Ok. I'm seeing the problem now. Somehow the baseline adjustment must have been lost.
As a quick fix, you could install https://addons.mozilla.org/en-US/firefox/addon/native-mathml/, which makes the page look like that

I investigated this issue.

$ curl -sD - https://en.wikipedia.org/api/rest_v1/media/math/render/mml/3f62755bfb0cfae950981e324bcf06d4ba99c8d8 | grep 'x-mathoid'
x-mathoid-style: vertical-align: -0.583ex; width:1.819ex; height:3.176ex;

But I think for a good visual impression it should be more like about -1.5ex instead of -0.5.
@Pkra Do you know by chance, if that was already fixed in a recent MathJax version?

I've opened https://github.com/mathjax/MathJax-node/issues/233

At official version of MathJax-node also reports today
width="1.808ex" height="3.176ex" style="vertical-align: -0.52ex;"

thank you @Pkra

We know have a set of changes that would eliminate the problem, which I deployed to our beta.math test instance

$ curl -sD - http://beta.math.wmflabs.org:7231/wikimedia.org/v1/media/math/render/mml/72270158db956adb742cf5e5d4b723badf2e2b82 | grep 'x-mathoid'
x-mathoid-style: vertical-align: -0.581ex; margin-bottom: -0.757ex; width:1.819ex; height:3.176ex;

@Christian1985 Can you check if http://beta.math.wmflabs.org:8080/wiki/Garbenkohomologie looks good now. Since a lot of code was changed, I'm afraid that it might have broken the alignments in other locations.
I also regenerated this page
http://beta.math.wmflabs.org:8080/wiki/Help:Formula
even though it does not contain to much inline math.

See https://github.com/wikimedia/MathJax-node/pull/22 for the current progress

@Physikerwelt now there are on the page many formulas which wont be rendered. Instett I got the message "Cannot get mml. Server problem.".

@Christian1985 That's a problem with the test-server config. It can not handle too many request in parallel. It should go away when you run action=purge

In T135423#2303648, @Physikerwelt wrote:

@Christian1985 Can you check if http://beta.math.wmflabs.org:8080/wiki/Garbenkohomologie looks good now. Since a lot of code was changed, I'm afraid that it might have broken the alignments in other locations.

The in-lined formulae start below the text's base line in both Chromium and FF.

@mobrovac in a good or a bad way? Can you share a screenshot?

For me everything looks terrible compared to MathML rendering.
FF with Native MathML plugin:

Here's my screenshot for Chromium:

Pretty similar to yours, @Physikerwelt. Most of the in-lined formuale start lower than the text around them.

For me it looks like an improvement over the first screenshot of @Christian1985 and what was the intended behavior as described here http://beta.math.wmflabs.org:8080/wiki/MathAxisAlignment. @Christian1985 what do you think?

In T135423#2307251, @Physikerwelt wrote:

For me it looks like an improvement over the first screenshot of @Christian1985 and what was the intended behavior as described here http://beta.math.wmflabs.org:8080/wiki/MathAxisAlignment.

Yes, indeed, good point. I've forgotten to take a second look at the original.

Change 289312 had a related patch set uploaded (by Physikerwelt):
Update MathJax-Node version

https://gerrit.wikimedia.org/r/289312

Change 289312 merged by Mobrovac:
Update MathJax-Node version

https://gerrit.wikimedia.org/r/289312

Hello,

I think the bug is fixed. Thank you!

Christian