What is the data source for Jaamamõisa oja in this extent? This watercourse is not present in Keskkonnaportaal (EELIS). It is said to flow in sewers after Jaamamõisa tänav, but is it associated to e.g. sewers under Papli tänav in particular?

Note that ways at differerent layers (road, waterway) generally aren't supposed to be joined with shared node(s) like here: https://www.openstreetmap.org/way/1150884721
See https://wiki.openstreetmap.org/wiki/Key:layer