Since Edge is switching to Chromium next month, we could/should drop support for the older layout engine in v5. Thoughts @twbs/team?

Advantages:

• Use scroll-margin-top instead of pseudo hack (Use scroll-margin-top instead of pseudo hack #30273)
• Better fix for Flex container doesn't display correctly next to a legend #29712
• Use clip-path to simplify .sr-only class

Status: Keep an eye on legacy Edge usage, if it drops quickly enough we can consider dropping it.