Never heard of a "flyleaf bushing" so it could be a name the guy just invented......maybe like a "muffler belt"
However, worn bushings on a suspension system can cause problems: Rubber bushings can deteriorate quickly in the presence of oils (e.g., motor oil, mineral oil) and extreme heat and cold.
The flexibility of rubber also introduces an element of play in the suspension system. This may result in camber, caster, or toe changes in the wheels of the vehicle during high-load conditions (cornering and braking), adversely affecting the vehicle's handling. For this reason, a popular aftermarket performance upgrade is the replacement of rubber suspension bushes with bushes made of more rigid materials, such as polyurethane. Polyurethane bushes are also available for many vehicles with the same characteristics as the manufacturers original bushes, but with greatly increased durability. This is useful on vehicles that have a reputation for wearing out standard rubber bushes, but for which harder bushings with increased harshness of ride are not wanted.
Suggestion: Take your unit to a reputable alignment shop and have them check the suspension system for worn parts so you know