Django is very good at being backwards compatible. Deprecated functions emit warnings for a few releases before being removed. They are also documented.
Do you have some examples? Are you sure you are not confused with dependencies?
The release notes mention less than ten deprecations related to django. Other stuff which is not supported anymore is mostly non supported database versions.
The Django incompatibilities is a small problem. If you do sign-up for the theory that it's better to use its ecosystem, the changes on the related projects are much larger.