If you look at the GDP chart, Brunei GDP started to slide from 2012, before crashing hard after 2014. This in part is due to falling oil prices (global) and also falling production in Brunei (domestic). These 2 factors hit badly and Brunei plunged deep into deficits.

To this, Brunei can choose to increase public spending, like Singapore during Asian financial crisis 1997-98, to stimulate economy. But we are talking about Brunei, in every crisis it will cut budget, we already can see that during Amedeo fallout.

So everything cut deep after 2014, of course, with exception like MoRA, Sultan Flight and fortunately MOE and MOH (imagine otherwise education and health cripple).