The suspension threatens to cruel the Rabbitohs' entire 2023 campaign after Mitchell incurred a grade-two dangerous contact charge for striking Frizell in the head in Sunday's 29-10 loss to Newcastle.
Tensions boiled over in the dying minutes at McDonald Jones Stadium when Mitchell led with his elbow as he moved in to tackle Frizell.
When Mitchell collected the Knights second-rower in the back of the head, a fracas broke out between the sides.
Frizell was uninjured and played the final two minutes but Mitchell went on report and to the sin bin.
He faced a nervous wait before learning his fate from the match review committee on Monday, then offered an early guilty plea to avoid risking a two-match ban.
With Souths having a bye this week, Mitchell will miss the round-27 blockbuster against the Sydney Roosters that is likely to decide which of the two bitter rivals progresses to the finals.
According to league historian David Middleton, the Rabbitohs hot-head now joins Roosters firebrand Victory Radley as the most sin-binned player in NRL history with nine dismissals.
Mitchell owned that dubious distinction outright with eight sin-binnings entering the season before Radley surpassed him with two more earlier in the year.
Although Mitchell had been a relative cleanskin in 2023, his first offence of the season may yet prove one of the most costly of his career.
If the Roosters beat lowly Wests Tigers on Saturday then defeat Souths sans Mitchell, the Rabittohs will potentially miss the finals for the first time since 2017.
Mitchell's latest ban comes after he was suspended for the Rabbitohs' run to the 2021 grand final for a high tackle on Joey Manu in the final weeks of that season.
Little wonder Souths coach Jason Demetriou lashed his ill-disciplined No.1 for his unnecessary shot on Frizell.
"It's just silly from Latrell," Demetriou said on Sunday.
"He got his medicine."
Demetriou said after the Knights game that Blake Taaffe would play fullback in Mitchell's absence.Â
Taaffe most recently filled in when the Rabbitohs lost their marquee man to a long-term calf injury earlier this season.
"Blake Taaffe is doing a great job," Demetriou said.
"He's played some good footy for us this year."
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