Start with a known SDR item
Google documents over-saturated SDR as a possible consequence of always-enabled HDR on its streaming devices. Its display guidance points to Match content for this case. The useful observation is a range mismatch, not simply a preference for muted colours.
Choose an item known to be SDR and keep the television’s picture mode fixed. If the source format is unknown, do not label a vivid image proof of the documented problem.
Compare the output choice
Inspect Display and Sound on the Google streaming device and record the range configuration. Compare content matching using the same item. Note whether the received TV mode changes, if the television exposes that information.
Brightness and saturation can also be affected by TV processing. Avoid changing those settings during the range comparison. Otherwise a pleasing result cannot be attributed to the specific correction.
Keep the explanation bounded
If the known SDR item looks more appropriate after matching, retain that configuration and check another familiar source. If it does not, revisit source identification and the television picture settings rather than applying an arbitrary colour recipe.
The streaming box’s HDR capability is not proof that all sources should be converted into the same output range. This page explains Google’s documented comparison and makes no measured calibration claim.
Questions answered
Does every vivid picture indicate an HDR mismatch?
No. Confirm the source range and keep TV processing in the comparison.
Does matching add HDR detail to SDR video?
No. It changes the output presentation, not the original source.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.