My download speed decreases when SQM is installed

Installing and Using OpenWrt
1

I only define sqm in the upload section, the download values ​​​​appear normal, but sometimes I see 13-15 mbps, why is this happening while downloading?

200mbps download 30 mbps upload

	Xiaomi Mi Router 4A Gigabit Edition

	MediaTek MT7621 ver:1 eco:3
2

Because the sender doesn't have unlimited bandwidth?

3

When software stream offloading is enabled I can download 22-23 mbps from the same location, but when I enter the sqm session the download becomes 13-14 mbps.

4

sqm is supposed to slow down large bulk streams to keep voip and games interactive.