Switched to brand new chain, chain is slipping

So I got a brand new ebike with the following drive train:

Shifter: Shimano Deore SL-M6100-IR
Rear derailleur: Shimano XT RD-M8100-SGS, ShadowPlus, 12-Speed
Cassette: Shimano Deore CS-M6100, 10-51T
Chain : Shimano CN-M6100 128link(incl. master)

I kinda ruined the OG chain by leaving it in isopropyl too much, so i bought a new chain that is the exact same chain, and it came with 126link(including master).

New chain installed, text facing outward, master link arrows pointing in the right direction, chain matching with wide/narrow teeth on chainring, but it started producing this.
( cassette still is brand new as well).

Is it that one missing link, or something else?