Just a priori this does not seem very likely to me. If you have budget that needs spending, it is key to spend it inconspicuously because as soon as a higher-up finds out that you are just wasting it to maintain your yearly allocation, they will still conclude that you need less next year (and that perhaps you ought to be fired.)

You can order a training exercise that burns up a massive amount of fuel. You just have to make it seem plausible enough to only be considered incompetent, not malicious.

"driver training" -- "Yeah, I know it looks like they are just driving in circles, we almost had an accident from someone driving in a circle so we are practicing."

Sounds about right.

Same things happened at a university i worked at. Year-end spend!

Another explanation besides budget would be that fuel has an expiration date; regular petrol 3-6 months, diesel up to a year, after which it becomes gummy. It can be extended a bit with a stabilizer though.

But yeah, I can imagine militaries have a huge challenge stockpiling fuel without it expiring.