First of all, here is the one time when Renovate _won't_ update branches.
If you have edited a Renovate branch directly (e.g. to make a code fix to allow tests to pass again) then Renovate will stop all updates of that branch.
It is up to you to either finish the job and merge the PR, or rename it and close it so that Renovate can take back over again.
If new commits to the base branch - such as merging another Renovate PR - result in an open Renovate PR having merge conflicts, then Renovate will recreate ("rebase") any conflicted PRs.
This applies both to commits to dependency files such as `package.json` as well as lock files such as `yarn.lock`.
You should not ever need to resolve such conflicts manually.
You can disable this functionality by configuring `"rebaseWhen": "never"` (not recommended);
1. If you manually configure `"rebaseWhen": "behind-base-branch"`
2. If you have enabled "Require branches to be up to date before merging" on GitHub protected branches settings, and `rebaseWhen` has default value `"auto"`
It is possible to manually request that Renovate rebase a PR by ticking a rebase/retry checkbox on GitHub or GitLab, or by adding the label "rebase" to a Renovate PR.
This label name is also configurable via the `rebaseLabel` config option too.