During the merge of Marriott Rewards (MR) with SPG, on April 16, 2018, Marriott updated the criteria for Lifetime elites to include what was known then as Lifetime Platinum Premier (LTPP) for heritage MR elites who'd have 750 lifetime nights and 2 million lifetime points earned as of August 31, 2018 (discussion started here: Lifetime Marriott Rewards elite status (Pre-Merge 2018 and earlier) - FlyerTalk Forums). This counted earned nights and points only from the MR side. Eventually, Marriott renamed Platinum Premier to Titanium by shifting Platinum elite status to earning 50 nights/year and setting Titanium at 75 nights/year.

For those of us who were or close to LTPP, it set up night and/or points runs to get to 750/2MM by August 31, 2018: The Race to 2.0MM Points is On! - FlyerTalk Forums

And as noted in different threads across this forum, Marriott has expressed no interest in re-opening qualification to LTT just because of the hassle of figuring out what earned pre-merger vs. how to count anything that came over from SPG vs. what all the sources of earning nights and/or points in the Bonvoy era.

David

p.s. Expectation of where I'll be by 31-Dec-2025:

Nights Stayed: 19+3
Paid: 15+3
Redeemed: 4
Bonus Nights: 28
Promo: 11
CC: 17

2025 Total Nights: 50
Total Qualified Spend: ~$3,500

p.p.s. FWIW, what the LTT card and package looks like: https://www.flyertalk.com/forum/31791275-post973.html