Check here for example on site: https://ru.stackoverflow.com/posts/891304/timeline
If you look into the HTML source you will see that there is an extra space character right after the opening quote (code 171):
<title>Временная шкала для « (Id = 891304)» - Stack Overflow на русском</title>
This space has come from the strings concatenation (title + id), but in case of an answer there is no title (see here: Question title is missing in answer's timeline window title)
In case of no quotes around tile, like on any SE site with an English interface, two sequential spaces are interpreted as a single one, and no visible defect is observed in browser. But it is still visible via the HTML source of course.