People in the Magic: The Gathering community have been complaining about one overpowered "Oko, Thief of Crowns" from Throne of Eldraine, and it's easy to see why they want to get it banned in Standard format: the three-to-cast blue/green Planeswalker starts with high loyalty, it can defend itself against big creatures and small creatures, and it's great against many viable strategies in Standard.
If you still don't see why this card is broken, just watch MTG hall-of-famer Ben Stark explain it for you. During a recent MTG Arena livestream on Twitch, Stark says that planeswalkers that are cheaper to play are usually easier to attack but better against Control. However, he explains that Oko is a problem in Standard because the card doesn't have a vulnerability: It's great against small creature decks because you can create a 3/3 Elk token with your Food or smaller creatures; it's great against big creature decks because you can turn them into 3/3 with no abilities; and it's great against Control decks but it comes in early with high loyalty, by turn 2 or 3, so it's hard to counter. Stark points out that big creature decks, small creature decks, and Control strategies are pretty much all of Standard, so Oko is strong against everything in the format.
Watch Stark talk about it in the video below:
Many would agree that it's the most powerful Planeswalker card Wizards of the Coast printed, and it's easy to see why. If you need other MTG pros to explain it for you, Arix Lax also wrote recently wrote a piece on his Blogspot explaining how "parasitic mechanics" like Food must have influenced Oko's design.
If you need another MTG pro to explain for you, you can watch Matt Nass and LSV's video here.
Wizards of the Coast is aware that Oko is a problem in Standard, and Melissa DeTora recently addressed it during a livestream. WotC already confirmed that they will not make and ban and restricted changes before Mythic Championship VI but reminded fans that the next scheduled B&R announcement will be on Nov. 18.