If an abuse is obvious the bank may consider a SAR, but it is the businesses responsibility to use the funds correctly to allow the funds to be eligible for forgiveness. Following a money trail could be quite involved and beyond the scope of a lenders responsibility. Some issues may be obvious while others require a lot of analysis. If the question is an ethical one, that may be for a court to decide and whether you'd use a SAR based on your observations is likely a case by case issue.
In the link below - "He spent the money on child support, a Rolex Presidential, a 5.73 carat diamond ring, and even leased a 2019 Rolls Royce Wraith," and "When he met with investigators last week, Fayne denied spending the loan on anything besides payroll and business expenses...Fayne's attorney Tanya Miller said there was 'considerable confusion' about PPP guidelines and over whether owners could 'pay themselves a salary' when asked about the charges by CNN."
https://www.dailymail.co.uk/news/ar...nt-emergency-loan-Rolex-Rolls-Royce.html