My new monitor makes spreadsheets look like they were printed underwater

I bought a larger monitor for spreadsheets because my laptop screen was turning every budget review into a squinting contest. The new screen is physically bigger and somehow harder to read.

Text looks slightly fuzzy. Thin grid lines seem uneven. If I increase the scaling, menus become comfortable but parts of the spreadsheet feel enormous. If I reduce it, the sheet fits nicely and the labels look like they were printed underwater.

I blamed the inexpensive monitor first. Then I noticed that my laptop was sending it a resolution that did not match the number printed in the monitor's specifications. The display was resizing the image to fit, which may explain why nothing looked properly sharp.

Before returning anything, I want to simplify the setup. I will connect the monitor directly instead of through the dock, select the display's intended resolution, test a few scaling levels, and confirm which screen the operating system considers primary. I will also check the monitor input, cable capability, and text-smoothing setting one at a time. A screenshot is not enough evidence because it may look sharp when viewed on a different display, so I am using photographs and written settings to preserve the comparison.

The goal is not to win a specification contest. It is to make ordinary text comfortable for several hours without creating tiny controls or distorted images.

What sequence would you use to diagnose a blurry external monitor? At what point does the evidence justify returning the screen rather than continuing to adjust resolution, scaling, cable, dock, and application settings?