Apk not verifiying? Wasted about 500mb already

Fdroid keep saying apk is failed to verify. Everytime i want to download a big app, i have to download through the browser.
My mobile data is a bit slow but it shouldnt have any problems, i am not understand why this is happen.
The gui bugs sometimes, the percentage is switching between different numbers.
The app screenshots and icons are all missing, although i dont really mind it.
Am i the only one experiencing this?

So you have more than 1.5Gb free storage space on the system partition?

Device? Android version? F-Droid Client 1.15.2?

I have 31gb free space
Device oppo f11 pro
Android version 10
And yes 1.15.2

But works fine with smaller apps?

Which big apps show this error?

I was trying to install termux 90 ish mb app. I think it has something to do with my net, but its weird, since downloading from browser just works. I have most of the simple tools installed and they work fine, rarely i get the gui bug with small app sizes

on my android-10 under Settings/memory I can see

“internal memory” (= “system partion”)
“sdcard”

do you really have 31gb of free internal memory?

I cant find the settings you are talking about but here is a photo