Why can you tell me??
Without any context, it's hard to answer this. My GUESS would be that you found someone who decided to charge a lot for a Roku, and decided that referring to it as "2021 model" would make it sell.
What model is it actually? How about a link? The current Roku Ultra is the 4800, released in October 2020.
Where are you seeing these prices?
To my knowledge the latest Ultra released is the model 4800, released in October 2020.
Ultra is normally $99.99, currently on sale from Roku thru June 12, 2021 for $69.99.
Obviously a 3rd party seller that is attempting to make a huge profit because someone doesn't do some research before buying. I'd stay far away from any such dealer.
It's on Amazon right now for $69, assuming you are in the US: https://www.amazon.com/Roku-Streaming-Bluetooth-Headphone-Shortcuts/dp/B08G9TJWW9/
Any time I see a listing that just lists a year, or worse "latest model", I pretty much avoid it altogether. Always check the model number.