Ok, so after going through this entire thread over and over again, it's clear to me that the most up-to-date MSM tool that is actually working and has gotten me back to stock in late 2022 is this one:
本站提供一加全机型ROM下载，包括一加Ace 2V、ACE2、Ace/10R、一加10 Pro、9Pro、9RT、9R、8T、8 Pro、一加8、7T Pro、7T、7Pro等全系一加机型的升级全量包、降级包、9008线刷救砖包等各种官方和原厂ROM，全部资源完全免费，不限速，无需登录
Now just for reference, I had a completely BRICKED OnePus 9 LE25AA (Global Version), and this MSM has gotten me back to Android 11 on OOS 18.104.22.168. Just to help those out who are looking at this thread in 2022 and aren't wanting to look through this entire discussion. View attachment 5711373
Hope this helps you out!