I completely agree with the previous comments. We have about 350 clients, and we carefully designed their browsing experience using GPOs. Giving the end user the possibility to escape our policies by simply switching to personal browsing mode is unacceptable. I can foresee a ton of helpdesk tickets because of that.
The so-called solution to restrict the login pattern to the user's Entra ID Account does not prevent the enduser to use the personal browser - and pressing the switch button "makes the browser remember your choice for that URL" (quote) will lead to major confusion. Statements like "Switching from the work browser window to the personal browser window will be default on in future versions of Edge for Business" are even more scary.
We need the possibility to completely disable the switch to the personal browsing experience, plus hiding the button. We will stick to Edge v114 (Extended Stable release) as long as possible, and hope this problem is going to be fixed soon by introducing new GPO Settings.