To expand. The bare copper is not correct but is not the most serious problem. The bare conductor is the CPC (earth) core and should be sleeved for identification pusrposes, however it should not be live or dangerous to touch. But all junctions between cables must be installed in suitable purpose-made enclosures, so that you only see the grey outer sheath of the cable entering, not the blue and brown cores nor the connectors joining them. Leaving those exposed is unacceptable as they are not mechanically secure nor protected against being touched.
'Work' of that standard, as hinted at above, indicates a general disregard of both the regulations and accepted practice, even if it does not present an immediate threat to life. You just don't do it like that (although it's certainly not the first time nor will it be the last.) And also as mentioned above, hidden joints are undesirable and usually a sign of bad planning or damaged cables. They are often a sign of modifications to existing wiring; in normal circumstances the should not be found in new work as there are usually better ways to arrange things, so that all connections are made inside fittings where they are accessible.