Transition chords?

Hello everyone. I have found out that Chinese pop song arrangements have these "transition chords" mostly in the last chorus which is the climax part.

I have no idea how did they apply it and which theory does it related to. Here are two examples:

1. 有一種悲傷 A Kind of Sorrow

This song is originally in the key of G major. In the chorus at 1:04, the chord progression is:
Cmaj7 - Cdim7 - Bmin7 - Emin7
At 2:32, the song is transposed up to Ab major, as a climax and the chords are basically (Db - Eb - Cm - Fm)
At 2:54, however, the chords are not directly transposed. The bass line goes like: Db  -  Eb F G Ab  -  C  -  F
The second bar isn't just a bass line, but the whole orchestra changes which is a complete chord change. Does anyone have any idea what they are?

2. 说谎

Right after 2:22, there are 3 different chords with 3 bass notes played to match the lyrics, which is something similar to the 1st example.

There are still a lot of songs which use this technique but I could not think of them at the moment. Please help me to figure out what is this all about. Thank you!

Ab to Gb/Ab (or you could say Ab9sus4 at that 2:54 mark.