Air Drop File size Limit

I have the same problem transferring large files (>6GB) between my 2019 iMac (Catalina 10.15.4) and iPhone 11 (13.5). Anything below 6GB in one file works fine, anything larger breaks off right after the start.

There is 50 GB space on the phone, so that can't be the problem. All devices are up to date.

Not sure what to try next. Did the restarts and firewall on/off, waved incense between the devices to clean the air, all possible options and nothing works.

Thanks for your help.