I think there was a lot more going on than that. Benioff and Weiss wanted out. They wanted to collect all their accolades and move on to fresh IPs. HBO was happy to give them more money and time to construct full-length seasons, but they chose to push the last two with shorter runs.
I think if they had handed the show off to fresh showrunners ready to build on the existing plot threads and pacing of the show, we'd be looking back on it very differently.
Rumor is he dies in the first 20 minutes. To "make the plot intense and unpredictable".
Nothing against the actor, but creating a boring character to hang the plot on was always a dumb decision for a franchise with lore like Mortal Kombat.