Sandisk has some logic for write protection somewhere that is buggy. Most of their sticks at some point run into it at some point;
https://www.google.com/search?q=sandisk+ultra+fit+usb+3.1+read+only&rlz=1C1GCEU_nlNL936NL936&oq="Sandisk+Ultra+Fit+USB+3.1"+read&aqs=chrome.1.69i57j33i160l3.8946j0j7&sourceid=chrome&ie=UTF-8
A Dutch Tech/Nerd size which is very good for user reviews also says it is slooooowwwww;
https://tweakers.net/pricewatch/1155869/sandisk-ultra-fit-usb-31-32gb-zwart/reviews/
There are also some big test bemchmark reviews about USB stick in general at that page.
But to be honest, better to just test it yourself and see how it behaves on the RPI4 and OS you are using. USB stick is always a trade of in speed/size/storage/price.
Perhaps the Samsung FIT Plus might be a better choice for speed for the next batch, but pricing go up fast as you guys probably know already;
https://tweakers.net/pricewatch/1230799/samsung-fit-plus-32gb-zwart/reviews/
Anyhow, just tech/nerdy feedback, not a complain 