X_SIDE_EFFECTS_ANCHOR_STALE
Means
a SIDE_EFFECTS_ANCHORS row naming a module nothing declares
Typical cause
the module was renamed, deleted, or its package stopped declaring it side-effecting, so the row argues for an anchor that protects nothing while still reading as a rule in force — X_TIER_FLOOR_STALE is the identical half of FLOOR_ABOVE
Fix
delete that row from SIDE_EFFECTS_ANCHORS in scripts/lib/side-effects-scan.ts, or point it at the module it was written for