Have you looked in Settings, Update & Security, Windows Update, View Update History to see what Windows Quality Updates (in particular) and/or Other Updates may have been applied to Windows over the last few days to a week?
Since 21H1 is not yet a general release, but in beta (AKA Insiders) state, this could be Windows related, too.
It is pretty much impossible for those who aren't using what I'll call "bleeding edge" versions of Windows to replicate issues such that they necessarily apply under the ecosystem you're using. If you are not already a member of the Windows 10 for Screen Reader Users Group, and specifically their Insiders subgroup, I'd encourage you to join both and ask on the Insiders subgroup, where someone may be able to attempt replication under the same environmental constraints that you have.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
Always remember others may hate you but those who hate you don't win unless you hate them. And then you destroy yourself.
~ Richard M. Nixon