Pacing is highly individual, it depends on fitness level and (realistic) race ambitions.
Front pack paces according to “survival of the fittest”, these days XCM is like XCO, fast starts, survival to the end. You have to go with your competitors. This is also important for mental reasons, it’s “easier” to push yourself in a group.
For Mid/rear pack an even pacing may be more sensible. Depending on fitness level climbs will be taken somewhere between upper tempo to upper endurance zone. If you still have something left in the tank you can always crush the competition on the last two climbs … but quite frankly, almost everyone goes to fast in the beginning, being in the pack, race fever. Difficult to hold back.