Tether Recovery Glitch
During the initial release of the game, Isabelle was thought by many players as the first character in Ultimate to suffer a tether recovery glitch with her Fishing Rod. This allowed the move to teleport Isabelle randomly on stage during her recovery. While game updates has attempted to remove this glitch, the issue remains unsolved. The glitch not only occurs on one character, but primarily applies to all characters with tether recoveries who also suffer the same issue.
List of Characters Affected By Glitch
Some to most characters can perform this glitch.
A variation of Tether Recovery Glitch exists that resulted some characters sliding while retaining their momentum although considered a technique. A notable example, Samus can double jump and tether at a certain height at the same time while moving forward. This technique also works with previous Smash title.
There is currently no explanation on how the glitch can be performed. In most cases, when recovering using a tether grab, it will randomly cause players to go through stages or can teleport on-stage. CPUs have the tendency to do the same making them easier to perform this glitch, but not intentional.