Lots of little things. See these:
https://suzukimarauderowners.forumotion.com/t106-low-power-solved
https://www.motorcycleforums.net/threads/suzuki-marauder-125-power-loss-problem-please-help.49036/
https://www.howtomendit.com/answers?id=188977
Ougf, November 2023