A deprecation means that Microsoft intends to remove the feature or capability from a future major release. This means that you need to have a future plan which includes taking care of those parts in your solutions that uses features or capabilities which are being deprecated.
Deprecations are coming to model-driven apps 2021
Form footers won't be supported Form footers deprecation and low-density form headers won't be supported Low-density form headers deprecation. These two deprecations will apply with the 2021 Release Wave 2 (October 2021).
- Important changes (deprecations) coming in Power Apps, Power Automate, and customer engagement apps
- Deprecation of the regional Discovery Service and its replacement with the global Discovery Service