Affiliate links being included in the app, despite community objections? The lead dev using donations to pay for holidays? Those are a couple that come to mind.
If the donation is framed as a single developer benefitting it should be fine, but at least when I was donating that was framed as donations to the project which suggests something else.
I'm fine with this use, rewarding a developer, but neither was this transparent nor was it fair for all others working on the project (and supposedly getting cost claims refused).
Guys in OM core dev team paying for hosting, app accounts, legal questions, etc(AFAIK, they subsidize all that from their own money because donations are not enough).
On top of that, they contribute years of man-hours for free to the project. I believe it is completely fair for hard-working dev to use donated money to have some rest.
Imo, consumers of all that good are too spoiled to also require strict discipline or transparency or even hating original authors(as seen on HN).
Hosting etc. expenses are a minor fraction compared to OM's donations inflow. And its enough to hire devs, the first dev was hired more than two years ago, but they have been hiding this fact to look more poor and attract more donations.
Even long-term active contributors have been denied even totals information about donations and got to know about first hire by chance about a year since the fact.