diff --git a/src/sentry/api/helpers/deprecation.py b/src/sentry/api/helpers/deprecation.py
index c22248c702c8f0..bf6483b6e9fbbf 100644
--- a/src/sentry/api/helpers/deprecation.py
+++ b/src/sentry/api/helpers/deprecation.py
@@ -132,6 +132,8 @@ def get(self, request):
     :param key: The key prefix for an option use for the brownout schedule and duration
                 If not set 'api.deprecation.brownout' will be used, which currently
                 is using schedule of a 1 minute blackout at noon UTC.
+    :param url_names: A list of URL names that are deprecated if an endpoint has multiple URLs
+                      and you need to deprecate one of the URLs.
     """
 
     def decorator(func: EndpointT[SelfT, P]) -> EndpointT[SelfT, P]:
diff --git a/src/sentry/constants.py b/src/sentry/constants.py
index a48f5bd1a9ded5..aebadfa7be2d89 100644
--- a/src/sentry/constants.py
+++ b/src/sentry/constants.py
@@ -7,7 +7,7 @@
 import os.path
 from collections import namedtuple
 from collections.abc import Sequence
-from datetime import timedelta
+from datetime import UTC, datetime, timedelta
 from enum import Enum
 from typing import cast
 
@@ -1053,3 +1053,7 @@ class InsightModules(Enum):
     "dsr": "visual basic 6.0",
     "frm": "visual basic 6.0",
 }
+
+# After this date APIs that are incompatible with cell routing
+# will begin periodic brownouts.
+CELL_API_DEPRECATION_DATE = datetime(2025, 5, 15, 0, 0, 0, tzinfo=UTC)
diff --git a/src/sentry/issues/endpoints/organization_group_suspect_flags.py b/src/sentry/issues/endpoints/organization_group_suspect_flags.py
index 0378dc4b8cffbc..d170b0b2f04ea8 100644
--- a/src/sentry/issues/endpoints/organization_group_suspect_flags.py
+++ b/src/sentry/issues/endpoints/organization_group_suspect_flags.py
@@ -8,8 +8,10 @@
 from sentry import features
 from sentry.api.api_publish_status import ApiPublishStatus
 from sentry.api.base import region_silo_endpoint
+from sentry.api.helpers.deprecation import deprecated
 from sentry.api.helpers.environments import get_environments
 from sentry.api.utils import get_date_range_from_params
+from sentry.constants import CELL_API_DEPRECATION_DATE
 from sentry.issues.endpoints.bases.group import GroupEndpoint
 from sentry.issues.suspect_flags import Distribution, get_suspect_flag_scores
 from sentry.models.group import Group
@@ -32,6 +34,7 @@ class ResponseData(TypedDict):
 class OrganizationGroupSuspectFlagsEndpoint(GroupEndpoint):
     publish_status = {"GET": ApiPublishStatus.PRIVATE}
 
+    @deprecated(CELL_API_DEPRECATION_DATE, url_names=["sentry-api-0-suspect-flags"])
     def get(self, request: Request, group: Group) -> Response:
         """Stats bucketed by time."""
         if not features.has(
diff --git a/src/sentry/issues/endpoints/organization_group_suspect_tags.py b/src/sentry/issues/endpoints/organization_group_suspect_tags.py
index ffb10dae663286..73d33b00b93ca8 100644
--- a/src/sentry/issues/endpoints/organization_group_suspect_tags.py
+++ b/src/sentry/issues/endpoints/organization_group_suspect_tags.py
@@ -6,8 +6,10 @@
 from sentry import features
 from sentry.api.api_publish_status import ApiPublishStatus
 from sentry.api.base import region_silo_endpoint
+from sentry.api.helpers.deprecation import deprecated
 from sentry.api.helpers.environments import get_environments
 from sentry.api.utils import get_date_range_from_params
+from sentry.constants import CELL_API_DEPRECATION_DATE
 from sentry.issues.endpoints.bases.group import GroupEndpoint
 from sentry.issues.suspect_tags import get_suspect_tag_scores
 from sentry.models.group import Group
@@ -17,6 +19,7 @@
 class OrganizationGroupSuspectTagsEndpoint(GroupEndpoint):
     publish_status = {"GET": ApiPublishStatus.PRIVATE}
 
+    @deprecated(CELL_API_DEPRECATION_DATE, url_names=["sentry-api-0-suspect-tags"])
     def get(self, request: Request, group: Group) -> Response:
         """Stats bucketed by time."""
         if not features.has(