How do rewards for mixed threat level tempered investigations work?

So I know that monsters are separated into three threat levels and higher threat levels have successively higher rewards. But how do rewards from investigations with tempered monsters of varying threat levels work? For example, if I have a tempered Pukei-Pukei and tempered Bazelgeuse investigation, will my rewards be Tier 1 (from Pukei-Pukei) or Tier 2 (from Bazelgeuse)?

Solution 1:

Based on a Pukei-Pukei/Bazelgeuse investigation I just ran with friends, your rewards can be from Tier 1 and Tier 2. I received Mysterious Feystones, which do not drop from Tier 2 tempered investigations, and one of my friends received a Warped Feystone, which do not drop from Tier 1 tempered investigations.

Solution 2:

As of the Iceborne update, the threat level of tempered investigations is shown on the quest info page. The quest's level and rewards are based off the first monsters shown, even if higher threat monsters are also present.