Flag filter in Overview tab only updates donut chart; trend graph and top % remain repo-wide

[Kobby-Bawuah]

Describe the bug
When selecting a flag in the repository Overview view, the donut chart (right) updates to the selected flag, but the trend graph (left) and the top “Coverage on branch” percentage continue to show entire repository coverage. This creates mismatched numbers on the same page and is confusing—especially for monorepos.

Environment (please complete the following information):

• System: Observed in Codecov web UI on production; repo is a monorepo with multiple flags

To Reproduce
Steps to reproduce the behavior:

1. Open a repository in Codecov.
2. Go to Coverage tab → Overview subtab.
3. Use the Flags selector (bottom/side filter) to choose one or more flags.
4. Observe:
   ✅ Donut chart updates to reflect the selected flag(s).
   ❌ Trend graph (left) still shows repo-wide coverage over time.
   ❌ Top coverage % (“Coverage on branch”) remains repo-wide.

Expected behavior
Either:
Option A (preferred): When a flag is selected, all metrics on the Overview page (donut, trend graph, top % summary) respect the flag filter; or
Option B (UX clarity): If only the donut is meant to filter, clearly indicate that the trend graph and top % are repository-wide, with an inline hint or tooltip and a link to the Flags tab for flag-specific trends.

Additional context
See ticket in linear ticket for more context

[linear]

CCMRG-1856