Light from a low window catches a tile edge, and one corner appears higher than the next. Wider grout alone may not explain what you are seeing. Lippage describes a height difference between adjacent tile edges.
The Tile Council of North America’s lippage guidance discusses the relationship between installation allowances, tile warpage and other conditions. Acceptability depends on the applicable specifications and installation, so a single number copied from an unrelated project is not a reliable verdict.
Describe the location clearly
Photograph the area in ordinary light and note which edges are involved. Include a wider view so the installer can find the spot. A dramatic low-angle photograph may highlight a difference, but it should not be the only evidence offered.
Record the tile product, layout and installation date if known. Ask whether the concern is limited to one edge or repeated across the floor. Do not remove grout or disturb a tile merely to create a clearer photograph.
Ask for the relevant assessment
A qualified installer or independent assessor can consider the substrate, tile characteristics, layout and agreed standard. Ask them to identify the requirement they are using and explain how the observation was measured.
If discussing a proposed large-format installation, raise this question before work begins. Review the tile manufacturer’s instructions and have the installer explain the planned layout and preparation. A sample board may help with appearance, but it cannot prove that an entire floor will meet the required standard.
Keep safety separate from an aesthetic disagreement. If an edge creates a practical trip or mobility concern, restrict use as appropriate and obtain prompt professional advice. Avoid attempting a cosmetic fix that could conceal the problem without addressing it.
The most useful conversation is specific: this edge, this product, this installation requirement and this proposed remedy. That gives both homeowner and installer more to work with than a general claim that the grout lines look wrong.