Are robot window cleaners safe to use on outdoor high-rise windows?

Most current models include a safety tether and multi-stage power-failure protection that keeps the unit suctioned to glass for up to ~20 minutes after a power loss. Reviewers still recommend supervising the first few runs on high windows, attaching the safety rope to a solid anchor, and avoiding use in wind or rain. Frameless or single-pane exterior windows can confuse edge detection on some models.