XmlDoc is displayed along with the summary tag
Rider uses FSharpXmlDoc.FromXmlText(xmlDoc) -> xmlDoc.UnprocessedLines to get xml documentation text.
And if earlier for library entities there was a summary inner text there, then, apparently after https://github.com/dotnet/fsharp/pull/11454, UnprocessedLines contains text along with the summary tag, which looks like a regression.
Rider 2021.1 (old behavior)

Rider 2021.2 Dev (new behavior)

It seems to me it has something to do with how the documentation is read here https://github.com/dotnet/fsharp/pull/11454/files#diff-56fbb9330ceb81afbfa2ea19c8b4bb3946a732f8ffb128f0d1435884808e06e8R250
Just to note, Rider hadn't used the UnprocessedLInes member before #11454. I'd expect UnprocessedLInes to indeed contain the tags (since the lines are not expected to be processed in any meaningful way, so it seems correct), but I'd expect there to be another member that preserves the previous behaviour, i.e. cleans the docs.
Yeah, we seemed to regress something here. We don't see this in VS though. I know our tooltips code is pretty complex though. Would you be able to use the approach we do?
Would you be able to use the approach we do?
Yup, we're going to do a similar processing on our side too, it's just seemed reasonable to report the regression in case there're other FCS clients might be using the APIs in question.