On the inside surface
Indoor moisture can condense on cooler glass. Room humidity, glass temperature and air movement all matter. This alone does not prove the window has failed. Persistent moisture or surrounding damage deserves assessment.
On the outside surface
Exterior condensation can form in certain weather conditions. Note when it appears and whether it clears. Surface condensation is different from moisture trapped inside a sealed glass unit.
Between the panes
Haze or droplets inside the sealed space may indicate a problem with the insulated glass unit. Cleaning the accessible surfaces will not reach that space. Confirm the location before discussing glass-unit or whole-window replacement.
What to record for an enquiry
Note which surface is affected, when the moisture appears, how many windows are involved and whether there is staining or damage nearby. A photo from a safe indoor position can help a follow-up discussion. Do not dismantle the window to investigate.
Further reading : Renewal by Andersen — window condensation questions and answers.
This guide is a starting point for an enquiry. The cause and appropriate work require assessment of the actual window and site.