These roads connect, the alley is Kiệt 112 Phan Châu Trinh.

#OsmAnd

This crossing does not exist. There is only a ranger house at this location. There seems to be only one road between QL14C and Sa Thay, the southern one (osm.org/way/815117440). Either the northern road (osm.org/way/155749926) has moved, or it doesn't exist anymore. For now I've disconnected the roads at this point to prevent routing mistakes (osm.org/changeset/162661089), but this should be fixed by a contributor with better local knowledge.

"Museum doesn't exist"
The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2025-01-21T15:15:53Z
POI name: Ethnographisches museum
POI types: tourism-museum
#organicmaps android

"The node probably refers to the nearby Elephant Hotel"
The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2025-01-21T15:15:53Z
POI name: Big building
POI types: tourism-attraction
#organicmaps android

In context of overlay "Places" – Cà Phê Dunkin' Donuts (Cafe) – osm.org/node/5837899818 via StreetComplete 59.3:

Seems permanently closed

The wholesale market hall is here