Characters like Jiren and many other fighters from the Tournament of Power, the top brass of the Red Ribbon Army, and certain forms of Majin Buu could all be interpreted as leaving something to be desired.

Source: https://www.cbr.com/dragon-ball-super-gas-worst-villain/

Jiren is likely to charge at Zeno and attempt to overwhelm him with brute force.

Source: https://www.cbr.com/dragon-ball-jiren-characters-beat-defeat-fight/

Jiren is strong enough to trigger Goku’s first transformation into Ultra Instinct power, but is surprisingly cryptic when it comes to this important character.

Source: https://www.cbr.com/dragon-ball-akira-toriyama-best-forgotten-character-arcs/

Kefla's defeat is only a matter of time when Jiren is involved.

Source: https://www.cbr.com/dragon-ball-jiren-characters-beat-defeat-fight/

's climactic battle against Jiren the Gray served as one of the franchise's highlights.

Source: https://www.cbr.com/dragon-ball-super-will-goku-rematch-jiren/

Ultimately, it takes the team effort of Goku, Frieza, Android 17, and Vegeta to weaken and finally overcome Jiren.

Source: https://www.cbr.com/dragon-ball-super-strongest-characters/

Unfortunately for Kefla, Jiren is far stronger than Ultra Instinct Goku, who beats Kefla without even being at the top of his game or fully understanding his new strength.

Source: https://www.cbr.com/dragon-ball-jiren-characters-beat-defeat-fight/