FamilySearch claims that Microsoft have ceased support for IE11. This is untrue, as it is in FULL support until October 14, 2025. That means that bugs and security problems will be patched.
However, the website intends to use types of code which are currently not in IE11. They might be added to other browsers, but won't be added to IE. Until these features are defined and supported in browsers, FS can't use them, so IE will work as it did before.
I tend to use Edge these days, slowly getting used to its foibles. Some features of IE11 are missing from Edge, such as the ability to remove cookies selectively. They are now stored in an internal database without any documented access.
I've also noticed that the text on my own website looks better when rendered in Edge than in IE11. My gut feel is that it used to look better in IE than it does now. I wonder if this is a "feature" put there specifically to nudge us towards moving?
I always avoid Chrome because of the enormous amount of data it ships off to Google. Their stuff is extremely intrusive. An acquaintance was surprised to discover how much his Android phone had logged about his weekend away. It had told Google which hotel he stayed in, which restaurants he had visited, and how long he had spent there, just so that they could plague him with ads for similar places.