diff --git a/changelog.d/14433.misc b/changelog.d/14433.misc
new file mode 100644
index 000000000..08a350b13
--- /dev/null
+++ b/changelog.d/14433.misc
@@ -0,0 +1 @@
+Fix mypy errors introduced by bumping the locked version of `attrs` and `gitpython`.
diff --git a/scripts-dev/release.py b/scripts-dev/release.py
index c82c58c54..bf47b6c71 100755
--- a/scripts-dev/release.py
+++ b/scripts-dev/release.py
@@ -219,9 +219,7 @@ def _prepare() -> None:
                 update_branch(repo)
 
             # Create the new release branch
-            # Type ignore will no longer be needed after GitPython 3.1.28.
-            # See https://github.com/gitpython-developers/GitPython/pull/1419
-            repo.create_head(release_branch_name, commit=base_branch)  # type: ignore[arg-type]
+            repo.create_head(release_branch_name, commit=base_branch)
 
         # Special-case SyTest: we don't actually prepare any files so we may
         # as well push it now (and only when we create a release branch;
diff --git a/synapse/streams/events.py b/synapse/streams/events.py
index bcd840bd8..f331e1af1 100644
--- a/synapse/streams/events.py
+++ b/synapse/streams/events.py
@@ -45,9 +45,12 @@ class _EventSourcesInner:
 class EventSources:
     def __init__(self, hs: "HomeServer"):
         self.sources = _EventSourcesInner(
-            # mypy thinks attribute.type is `Optional`, but we know it's never `None` here since
-            # all the attributes of `_EventSourcesInner` are annotated.
-            *(attribute.type(hs) for attribute in attr.fields(_EventSourcesInner))  # type: ignore[misc]
+            # mypy previously warned that attribute.type is `Optional`, but we know it's
+            # never `None` here since all the attributes of `_EventSourcesInner` are
+            # annotated.
+            # As of the stubs in attrs 22.1.0, `attr.fields()` now returns Any,
+            # so the call to `attribute.type` is not checked.
+            *(attribute.type(hs) for attribute in attr.fields(_EventSourcesInner))
         )
         self.store = hs.get_datastores().main