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Nothing failed. Your write went to the primary. Your read went to a replica that hasn't caught up yet — 200 milliseconds behind, which is excellent by every metric on the dashboard.
Read replicas are how you scale reads. The cost is replication lag, and the cruellest version is when the missing data is your own.
Other people not seeing your comment for 200ms is invisible. You not seeing it looks like a broken product.
The fix isn't faster replication. It's routing:
| Read | Route it to |
|---|---|
| Your own data | The primary, or a replica known to be caught up |
| Everyone else's | Any replica — lag is fine |
Usually implemented as: after a user writes, pin that user's reads to the primary for a few seconds.