the LINQ docs C# samples consist of 7 projects to showcase IEnumerable and IQueryable
unfortunately much code unnecessarily invokes AsQueryable() despite simpler IEnumerable method implementations existing
[thus such guidance is poor as such AsQueryable() overhead can be avoided]
should update to useful modern C# v12 semantics [Primary constructors, Collection expressions, Span, is, etc]
calls being made to default parameterless ctor then assigning individual properties, rather than using parameterised ctors explicitly [or better yet primary constructor]
current analyzers also disclose numerous Warnings/Messages, emphasising poor guidance for today's coding
many cases of wastefully using Any(),Count(),LongCount etc when optimal coding available (e.g. Count, Length for Collections).
I will shortly submit a PR to explain problems & my suggestions.