diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f8263498c4da..dc64d4953085 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -176,10 +176,10 @@ supported:
   This defaults to `types-<distribution>` and should only be set in special
   cases.
 * `upstream-repository` (recommended): The URL of the upstream repository.
-* `obsolete-since` (optional): This field is part of our process for
+* `obsolete-since` (optional): This table is part of our process for
   [removing obsolete third-party libraries](#third-party-library-removal-policy).
   It contains the first version of the corresponding library that ships
-  its own `py.typed` file.
+  its own `py.typed` file, and the date when that version was released.
 * `no-longer-updated` (optional): This field is set to `true` before removing
   stubs for other reasons than the upstream library shipping with type
   information.
diff --git a/lib/ts_utils/metadata.py b/lib/ts_utils/metadata.py
index 4243129b64a7..b18fe5374eb2 100644
--- a/lib/ts_utils/metadata.py
+++ b/lib/ts_utils/metadata.py
@@ -24,7 +24,6 @@
 import tomlkit
 from packaging.requirements import Requirement
 from packaging.specifiers import Specifier
-from tomlkit.items import String
 
 from .paths import PYPROJECT_PATH, STUBS_PATH, distribution_path
 
@@ -299,12 +298,15 @@ def read_metadata(distribution: str) -> StubMetadata:
             assert num_url_path_parts == 2, bad_github_url_msg
 
     obsolete_since = data.get("obsolete-since")
-    assert isinstance(obsolete_since, (String, type(None)))
-    if obsolete_since:
-        comment = obsolete_since.trivia.comment
-        since_date_string = comment.removeprefix("# Released on ")
-        since_date = datetime.date.fromisoformat(since_date_string)
-        obsolete = ObsoleteMetadata(since_version=obsolete_since, since_date=since_date)
+    assert isinstance(obsolete_since, (dict, type(None)))
+    if obsolete_since is not None:
+        obsolete_table: dict[str, object] = obsolete_since
+        obsolete_since_version = obsolete_table.get("version")
+        obsolete_since_date = obsolete_table.get("date")
+        assert isinstance(obsolete_since_version, str)
+        assert isinstance(obsolete_since_date, str)
+        since_date = datetime.date.fromisoformat(obsolete_since_date)
+        obsolete = ObsoleteMetadata(since_version=obsolete_since_version, since_date=since_date)
     else:
         obsolete = None
     no_longer_updated = data.get("no-longer-updated", False)
diff --git a/scripts/stubsabot.py b/scripts/stubsabot.py
index 926b22c8a620..9b44186ee966 100755
--- a/scripts/stubsabot.py
+++ b/scripts/stubsabot.py
@@ -22,7 +22,7 @@
 from dataclasses import dataclass, field
 from http import HTTPStatus
 from pathlib import Path
-from typing import Annotated, Any, ClassVar, Literal, NamedTuple, TypedDict, TypeVar
+from typing import Annotated, Any, ClassVar, Literal, NamedTuple, TypedDict, TypeVar, cast
 from typing_extensions import Self, TypeAlias
 
 if sys.version_info >= (3, 11):
@@ -906,9 +906,9 @@ async def suggest_typeshed_obsolete(obsolete: Obsolete, session: aiohttp.ClientS
     async with _repo_lock:
         branch_name = f"{BRANCH_PREFIX}/{normalize(obsolete.distribution)}"
         subprocess.check_call(["git", "checkout", "-B", branch_name, "origin/main"])
-        obs_string = tomlkit.string(obsolete.obsolete_since_version)
-        obs_string.comment(f"Released on {obsolete.obsolete_since_date.date().isoformat()}")
-        update_metadata(obsolete.distribution, obsolete_since=obs_string)
+        obsolete_t = cast(dict[str, object], tomlkit.inline_table())
+        obsolete_t.update({"version": obsolete.obsolete_since_version, "date": obsolete.obsolete_since_date.date().isoformat()})
+        update_metadata(obsolete.distribution, obsolete_since=obsolete_t)
         body = "\n".join(f"{k}: {v}" for k, v in obsolete.links.items())
         subprocess.check_call(["git", "commit", "--all", "-m", f"{title}\n\n{body}"])
         if action_level <= ActionLevel.local:
diff --git a/stubs/binaryornot/METADATA.toml b/stubs/binaryornot/METADATA.toml
index 3146145847b8..431cf6be18ef 100644
--- a/stubs/binaryornot/METADATA.toml
+++ b/stubs/binaryornot/METADATA.toml
@@ -1,3 +1,3 @@
 version = "0.4.*"
 upstream-repository = "https://github.com/binaryornot/binaryornot"
-obsolete-since = "0.5.0" # Released on 2026-03-07
+obsolete-since = { version = "0.5.0", date = "2026-03-07" }
diff --git a/stubs/fpdf2/METADATA.toml b/stubs/fpdf2/METADATA.toml
index 98fa4b298c86..bc7b19c18581 100644
--- a/stubs/fpdf2/METADATA.toml
+++ b/stubs/fpdf2/METADATA.toml
@@ -1,7 +1,7 @@
 version = "2.8.4"
 upstream-repository = "https://github.com/py-pdf/fpdf2"
 dependencies = ["Pillow>=10.3.0"]
-obsolete-since = "2.8.6" # Released on 2026-02-19
+obsolete-since = { version = "2.8.6", date = "2026-02-19" }
 
 [tool.stubtest]
 stubtest-dependencies = ["cryptography"]
diff --git a/stubs/icalendar/METADATA.toml b/stubs/icalendar/METADATA.toml
index a530386b862a..a835cf4fb948 100644
--- a/stubs/icalendar/METADATA.toml
+++ b/stubs/icalendar/METADATA.toml
@@ -1,7 +1,7 @@
 version = "6.3.2"
 upstream-repository = "https://github.com/collective/icalendar"
 dependencies = ["types-python-dateutil", "types-pytz"]
-obsolete-since = "7.0.0" # Released on 2026-02-11
+obsolete-since = { version = "7.0.0", date = "2026-02-11" }
 
 [tool.stubtest]
 stubtest-dependencies = ["pytz"]