Which game is it?
Show us a link to your video or past broadcasts?
Also, show us your newer OBS-Studio logs as well.
Try to reduce frame rate to 30 fps (low motion game), and/or downscale to 720p (high motion game)
You can use more bitrate for better quality, at a cost of requiring more upload speed, and on Twitch, requires viewer's to have fast enough internet speed if your Twitch's account is without transcoding. There is a bitrate limit on Twitch.
https://stream.twitch.tv/encoding/