Uneven housework usually shows up before anyone says it clearly. The problem is that the pattern is often invisible until the resentment is already real.
One person keeps noticing everything first
If one partner is the person who sees the dishes, resets the room, remembers the laundry, and checks what is missing, that is work.
Shared chores still need one person to manage them
A chore may look shared on paper, but if one partner still plans, reminds, and follows up, the load is not actually shared.
The same tasks keep falling back to one person
Over time, you can usually see patterns in the chores that always end up being completed by the same partner.