So a couple things.
The way the bwlimit works is for both upload and download. If you set it to 10M, that impacts both download and upload.
You can use a per file limit to make sure that no one file saturates your bandwidth instead:
--bwlimit-file BwTimetable Bandwidth limit per file in KiB/s, or use suffix B|K|M|G|T|P or a full timetable
Personally on Linux, I use mergerfs which adds another layer on top and all my writes happen to a local mounted area and I upload that on a scheduled basis since you can schedule rclone move/copy from the local mount point to your remote.
This requires a bit more knowledge and some time to setup but I do have my process documented here:
animosity22/homescripts: My Scripts for Plex / Emby with Dropbox and rclone (github.com)
Doesn't really matter what backend as the process is still the same. That might be a bit much if you are not that well versed on the Linux side of things so sticking with the per file limit would be an easier route, but with less customization.