Tag wiki excerpts show up as truncated from the front for example in the Tags list view (where one can search for specific tag names):
Though all of these tags have correct excerpt texts, starting with capitalized words, e.g. contexts:
Contexts are used in Mathematica to organize defined symbols and avoid conflict between symbols that would otherwise have the same name. They are created when packages are loaded.
None of these tags were edited recently (within 24 hours), so I guess this is not a delayed updating issue.
Interestingly, none of these are truncated, though they are starting with practically "redundant information":