First, if you still have IE in your environment, a good read would be this blog entry: https://techcommunity.microsoft.com/t5/windows-it-pro-blog/don-t-wait-for-june-15th-set-your-own-ie-retirement-date/ba-p/3298143 The goal is to simulate your own "IE Death date" internally and do some small scale testing before IE actually goes away.
From a PolicyPak perspective, and specifically PolicyPak browser router, with IE going away/ gone, we have made some code changes to compensate for it.
Once IE is removed (for real, or using the simulation in policy from the Microsoft article above...) the follow behavior is now expected with latest CSE and PolicyPak Browser Router:
WILDCARD route to IE, it will open in EDGE. (not IE in Edge)
URL route to IE, it will open in EDGE (not IE in Edge.)
URL + Browser mode route (WITH "Open in Standalone IE" or "Open as IE in edge tab" .. it will open in EDGE IN IE MODE.)
So if you are using Browser Router, we strongly recommend upgrading your CSEs to the latest version.
But if you cannot / don't want to, know that you will get unexpected routing behavior. If you're using something BEFORE that, we cannot guarantee success when IE is finally removed on April 15, 2022