Nothing of the sort happened. From Jack Smith's report:
A significant challenge that the Office faced after Mr. Trump's indictment was his ability
and willingness to use his influence and following on social media to target witnesses, courts,
and Department employees, which required the Office to engage in time-consuming litigation to
protect witnesses from threats and harassment.
Volume I of that report is 174 pages of investigative findings, and we haven't seen volume II yet.
The idea that they were just lazy is completely ignorant of how long even normal federal cases take, let alone going against a former President with a penchant for stirring up a mob in his favor.
Those people did their jobs. The rest of the system failed them.