Season 5 contains a lot of content from season 1, but much of it is split into two groups from the same reward tier.
Tier 07 for instance has the Belga set as Group1 and the Nadine set as Group2. The blog post introducing Mission Pass during season 1 clearly shows that it had these two sets in different tiers, with Belga in tier 05 and Nadine in tier 10.
In season 1, tier 31 was a four-way choice between four cosmetic sets: the Belga and Nadine sets along with the Zamlord and Zelsius sets from tiers 08 and 18 respectively. If season 5 tier 31 is the same four-way choice, new players cannot get all four the way players in season 1 could. This is because Zamlord and Zelsius are also different groups of tier 13; Zamlord is Group1 and Zelsius is Group2.
- Tier 05: Belga set
- Tier 08: Zamlord set
- Tier 10: Nadine set
- Tier 18: Zelsius set
- Tier 31: Choice of one of the above four
- Tier 07: Belga set or Nadine set
- Tier 13: Zamlord set or Zelsius set
- Tier 31*: Choice of one of the above four (*Guessed)
It would be impossible to choose 4 sets in 3 tiers!
This dilemma is likely repeated with the contents of tiers 17 (Group1: Joker set, Group2: Lamia set) and 23 (Group1: Heretic Lord, Group2: Candy Crown), as all four of those were the four options in season 1 tier 35.
Meanwhile season 1 tier 32 is the same as season 5 tier 09 - a choice between the Chin Beauty Mark face paints (from season 1 tier 06) and the Photon Wings accessories (presumably from one of the tiers from 11 to 30). Presuming tier 32 is unchanged, we would be able to get both of those.
Of course they may have reworked tiers 31-35 in Season 5 so each is a repeat of one of the previous dilemmas (e.g. tier 31 being a mirror of tier 07, tier 32 being a mirror of tier 09 and so on). But this would require both ditching or adding the 25 SG reward in tier 32 and ditching the usual affix augment reward from tier 33. It's possible, and this is certainly a new type of season, but without the ability to see it I don't know if we can be confident.
It's also possible that the "Up to 1 group can be claimed." text for tiers 07, 09 and so on is incorrect and these tiers allow players to choose both groups. If so players will likely discover that in short order when people start reaching tier 7.
It's also also possible that for the first time, overtime mode doesn't stop at 35 but maybe continued to 40, allowing space to fit multiple choices in.
TLDR: Of the 8 returning outfits sets, PC players and newer Xbox players may only be able to obtain 6 in season 5 even though all 8 were possible in season 1. I hope I'm wrong. I really want to know.