You’ve increased your quality slider to a 100% increase in quality
Quality Multipltier → 2
That’s why the size is increasing.
Also noticed that you’re converting a HEVC to HEVC so it’s a pretty lossy conversion because MCEBuddy is remuxing HEVC → MPEG2 and then reconverting using your profile → HEVC
Try this instead, check the skip remuxing box in the expert settings page of the conversion task and select the MP4 Unprocessed profile. Because you aren’t doing any commercial detection of subtitle extraction it should work fine without any recoding. This will maintain the original quality/video.