Stem Splitter is internal to the computer. PG Music is licensing technology created by Zplane. You can read more about it +++ HERE +++ and I've copied the advertising blurb below:
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STEMS / High performance audio stem separation

Technology Details
STEMS TECHNOLOGY DETAILS

STEMS is our family of stem generation algorithms that is capable of separating any mono/stereo mixture into vocals, bass, drums, and ”other” (4 stems in total). Additionally, enhancement neural processing can be applied to further enhance each of the resultings stems. The enhancement is optional for each stem separately and let's you better balance performance and quality. Furthermore run our STEMS algorithms at standard latency of 2800 ms in contrast to the usual 12 sec latency. This enables fast reaction times even on slower CPUs.

STEMS PRO is our high quality version and balances quality and performance to run on desktop applications. In standard mode it is about 12 times realtime on a Apple Silicon M1 chip using only the CPU and maintains the highest industry standards in realtime stems processing.

STEMS EFFICIENT runs on low-performance CPUs, and is much faster than other available stem separation algorithms while offering competitive quality. It is approx. 34 times faster th

The Lyrics Generator requires an internet connection. I don't know what technology PG Music is using.

Jim Fogle - 2025 BiaB (Build 1128) RB (Build 5) - Ultra+ PAK
DAWs: Cakewalk by BandLab (CbB) - Standalone: Zoom MRS-8
Laptop: i3 Win 10, 8GB ram 500GB HDD
Desktop: i7 Win 11, 12GB ram 256GB SSD, 4 TB HDD
Music at: https://fogle622.wix.com/fogle622-audio-home