You don't have to try and find reasons that Tron took as long as it did to open, the reasons are there, even if you don't like them.
First you do have the pandemic. Anyone who thinks it didn't have an effect on construction related projects, is simply uniformed, naive, or just plain stupid. This leaves aside the fact that Universal may have kept construction going while WDW may have chosen not to. It was a decision WDW made on a macro level, not geared towards Tron.
And that leads into the overarching reason it took so long to open Tron, Disney had no reason to push construction. Once the initial schedule was blown, there was no reason to rush construction. You had the post covid closing pop of people going to the parks, you had the 50th anniversary, you had Rat coming on line, and Guardians soon thereafter. Other than just listening to people who don't budget the projects or pay the bills saying to build everything as fast as possible, there was absolutely no reason to push tron's construction/opening sooner than it did open. Why open it up right on top of Guardians, and them have nothing else coming on line? The pacing was done intentionally to keep to an overall plan of rides coming on line, not just pushing forward to get it done as fast as possible.