TLDR: Neither Edge (even after clearing cache) nor Chrome worked, but Firefox did load the redemption page.
Both Edge (v 114.0.1823.82) and Chrome (v 114.0.5735.248) gave me the same error when clicking the Redemption URL from the Microsoft Rewards email. In both cases the browser looked like it was about to load a page, but immediately appeared to redirect to an error:
This site can’t be reached
The webpage at***https://secure.rewardcodes.com/#/r2/1/[my redemption code here]***might be temporarily down or it may have moved permanently to a new web address.
ERR_ADDRESS_INVALID
I copied/pasted the URL from the email into Notepad which revealed that the # was not present, so I tried taking "#/" out of the browser's address box - but it just repeated the behavior.
I was about to file a contact complaint when I decided to try Firefox and maybe Brave, first.
Thankfully, Firefox (115.0.2) worked!