not a bug, but a feature. A worker slot is reserved for a citizen while he is walking. Therefore, for a long time it was difficult to provide the maximum number of workers: while some were still going to work, others had finished their workday and left. Then the developers allowed buildings to use slightly more worker slots. As a result, there may be 50 out of 45 workers in a building if new employees arrived faster than the day ended for those who arrived earlier.

It may not be a very elegant solution, but it helps to ensure stable operation.