I briefly worked in the Swedish public sector that had at that point been pushing for plain language for a while.

The problem they encountered is that the government still needs to be able to specify what they mean with precision. So what happened is that common words became overloaded with specific and often non-obvious legal meanings.

People at large with no clue how to "speak government" still didn't understand what the government said, but instead of a bunch of known unknowns it turned the language into a minefield of unknown unknowns.

(This got at least some attention notice during the covid pandemic, during which there was clear miscommunication between the government which used 'recommendations' to mean a strong non-legal mandate, and parts of the public which took it to mean helpful tips, like a movie recommendation)