There are multiple layers to Pong Krell’s acts available for review.
The first level is the most fundamentally basic: everything about the Clone Wars, including everything done by both sides has been shrewdly manipulated by Darth Sidious from the top down. On the Republic side, Sidious manipulates Republic strategy and forces through his role as Chancellor Palpatine. On the Separatist side, Sidious directly orders Tyrannus, who then executes Sidious’ goals. Sidious’ goal is the eradication of the Jedi and ruling the galaxy, something which he practically accomplished in Star Wars Episodes II and III.
Next, we get to Krell specifically and the events of the story arc. Indeed, it is Chancellor Palpatine - the Sith Lord Darth Sidious - who ordered Anakin's recall and Krell's instatement in the first place. Of course Sidious understands Krell’s condition and motives; Krell’s apparently ineffective methods of losing Republic forces to apparently inefficient suicide missions only looks bad if one is a good-faithed Republic defender rather than someone playing both sides of the deck who wins in any case and wins bigger the more that the Jedi and Republic suffer at the Republic’s losses. The Jedi’s loss is not merely through direct loss of Jedi but also through a debilitation of the Force; Republic troops choosing to kill themselves is a great win for the Sith.
Krell serves as a very effective tool for Sidious. Because Sidious is not a good-faithed defender of the Republic. Star Wars: The Clone Wars (2008) portrays Palpatine as helping or hindering each side to keep the war in a state of stalemate. Krell is being used by Sidious to serve that end. Pong Krell messes up the Republic’s Umbaran effort and could have damaged the entire Republic war effort.
For his part, Krell was a self-serving coward, and this opened the door to Sidious’ manipulations here. Krell legitimately had a vision of the Force where he saw the destruction of the Jedi Order. Krell then figured his way out was to try to curry favor with Dooku to survive that fate. Of course, unbeknownst to Krell is that Dooku served Sidious.
Sidious understood Krell’s motivations, was playing him, could perhaps have been testing him as a possible apprentice, and his specific acts of reinstating Krell in command and Anakin’s recall are proof enough that this was all just another of Sidious’ The Clone Wars machinations to send Jedi through the meat-grinder and further destabilize the Republic.