alarm bells are ringing

idiomPart ofalarm

alarm bells are ringing — idiom

1. used when signs of trouble make people start to suspect that something is wrong

1.idiom
Definition

used when signs of trouble make people start to suspect that something is wrong and needs attention.

Example

When sales fell for the third month, alarm bells were ringing in finance.

If a stranger asks for bank codes by text, alarm bells should start ringing.