Spreadsheets are excellent until they become infrastructure. The problem is not that a spreadsheet exists. The problem starts when the spreadsheet becomes the only place approvals, inventory, reporting, and customer status can be understood.
The warning signs are operational
Version drift is the easiest symptom to spot. Two people are looking at different files and both believe they are looking at the truth. The deeper symptom is delay: someone has to wait for another person to clean, send, unlock, or explain the sheet before a decision can move.
That is usually the moment to stop asking how to improve the spreadsheet and start asking what workflow the business is actually trying to run.
Build the smallest useful system first
The first system does not need every feature. It needs the main workflow, roles, permissions, status tracking, and reporting that helps the owner see what is happening without chasing updates.