Not OP, but...
1. Manager insisted on proper documentation of contract deliverables in case of a lawsuit. Higher manager said “Nah, waste of time. These companies never sue.” Lawsuit happened, case was overcomplicated due to poor documentation. Result of case still unknown, but should have been a slam dunk win for the company.
2. CFO decided to delay (not reduce) part of a regular disbursement to the owner in order to pay suppliers. If suppliers had not been paid, then product line gets shut down and company has an existential crisis. Disbursement eventually got paid, suppliers were happy, company thrived. CFO permanently in the dog house (e.g., lower bonuses, lower pay increases, left out of key meetings, etc.).
3. Any whistleblower in the US (maybe not “petty”). While whistleblower protections exist, it’s trivially easy in white collar work to find minor mistakes or question judgment calls. Retaliation can be trivially masked. Usually business as usual afterwards.
4. Taking alloted and approved vacation time — this happens a lot. Usually ends up causing the company to underperform after star leaves. I’ve seen it wreck a company when the person who left recruited all of their good people to his new company.
5. Documented firing of disruptive sociopaths who are friends with a senior manager (e.g., the CEO). I’ve seen this multiple times. Overall org usually becomes better due to lack of sociopaths, but the “hero” gets the shaft in the process.
6. Tactfully bringing up issues of fraternization by senior managers that may lead to conflicts of interest. I’ve seen this several times as well. Simple case is a senior executive who is married is sleeping with a low level employee. More complex is someone who is in an open marriage who is using junior employees not in his current department (but may be in his future department since they often make lateral moves) as a personal dating/sex pool. It usually ends up as a non-issue, until it becomes an issue (e.g., Ellen Pao).
7. I’ve literally seen someone fired for streamlining their department so much that it appeared that they didn’t do much work. The person was aware of the fact, and pitched it as “maintaining the system”. The management structure was “flattened” after that person was let go, things went to shit, and no one in senior leadership seemed to know exactly why.
8. Worker (not manager) reviewing vendors said that none of the vendors who submitted bids were able to do the work to standard based on work samples. Worker was replaced, contract went out, company lost millions due to... contractor not being able to produce product to standard.
There are many more...