Testing

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No, this is a hard-wired value in the code logic. You can verify it by looking at the page source and looking for og:description. For example the description of our latest preview of 5.4 has a description that is 202 characters long:

New Features in WoltLab Suite 5.4: Administrative Improvements

=>

(Code, 1 line)

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None that I'm aware of. This doesn't mean that there could be some dark magic happening on those third party sites, they are highly intransparent when it comes to these things.