Hello Maged100,
I speedtested my iphone in a wifi to fiber environment : upload was really good ... up to 50 MB. So to me iPhone is ok.
Then, I phoned Apple regarding this issue of low upload speed, but the guy on the phone first seemed not to be much helpfull at all is this matter. Apple said, all background apps shall be switched off, localization shall be off, etc ... I then thought I already did so (but may be not as completly as it would have been necessary...). It then seem nothing improved.
Finnally, by also tring to expend battery usage to maximum between two charges I applied some of following suggestions you can translate on the net if needed :
10 trucs simples pour économiser de la batterie sur un iPhone (francoischarron.com)
14 astuces pour économiser la batterie de votre iPhone (01net.com)
Then I checked again my upload speed and realized it most of the time improved of 3-4 MB which is 50% of my upload speed at home !
I so beleive iOs 15 and many background apps are using 3-4 MB of upload speed for some usages (localization, etc..) you can switch off if not needed. Doing so will free this 3-4 MB of uplaod trafic that is much needed on low and medium upload speed wifi and 3G-4G data connexions.
It would be great if all those apps and iOs using so much of upload flow could be limited to 10-20% of upload speed to keep iPhone available for user/owner... Does anyone have a suggestion to do so ?
Hope this will help you.
Have a good day :)