I've noticed the same thing. FWIW, it seems to only happen with some instances. For example, the linked Five Little Ducks example fails consistently for me, but replaying the example at the top of https://en.wikipedia.org/wiki/Cadence consistently works.

Edit: I think this might be related to T181897. The examples in the Cadence article were added since the change from Timidity to fluidsynth. The ducks example is older, and features the distinctive initial crackle described in T50029. If I preview a trivial change to the score (e.g. adding a comment) to force it to be re-generated, the new version in the preview doesn't have this issue.

T203873 is the solution, and would be trivial (thus was available in GCI) to do.

The faulty behaviour at https://en.wikipedia.org/wiki/Five_Little_Ducks disappears when some trivial changes to the Lilypond code are made. The smallest change I could introduce that would change the behaviour was to insert a space between the first \bar and the empty string ("") following it: from \bar"" to \bar "". (I also suggest that those \bar constructs are unnecessary/wrong and ought to be removed.)