That major change is at the level of the NVDA code itself, and while that is not something that should concern you directly, the possible side effects, particularly in reference to add-ons, is likely to.
The add-on application program interface (API) is to be updated to version 2021.1. This means add-ons not declaring support for NVDA 2021.1 in their manifests will be marked as incompatible. It doesn't matter if they're really incompatible or not, because this is the mechanism that is used to check compatibility, and invariably, due to a combination of factors, the add-on manifests sometimes don't get updated in perfect synchrony with the NVDA code. Plenty of add-ons that are now and will be perfectly compatible will end up being flagged as incompatible, and that will stop once the necessary tweak is made to their manifests.
All of that detail shouldn't concern you, either, but I wanted folks to be aware of why this is likely to happen. And it's most likely to occur when the beta versions of the next version of NVDA begin to show up.
If it occurs, please do not panic, it is most likely to get worked out once the incompatibility is flagged. If one of your favorite add-ons continues to be flagged as incompatible for a couple of days after you first see that, then do your add-on developer a favor and let them know. Many will be fixed before even a couple of days passes, which is why I don't suggest that everyone flood the developer's inbox immediately.
The purpose of this message is to make clear that the sky is well and truly not falling, though the possibility of it seeming like it is exists. There is almost certain to be a bump or two, at a minimum. Stay calm and carry on.
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