Answer
A user updates their profile, reloads, and sees the old version because the read went to a lagging replica. That breaks read-your-writes consistency.
Also accepted: read your writes, read-your-own-writes, read your own writes for read-your-writes.
Why
Common fixes: read the user's own data from the leader for a short while after they write, or send the write's position with the read so a replica answers only once it has caught up.