I uploaded several thousand files to a FTP server using explicit TLS/SSL. One particular jpeg file failed with an error message: "Transfer aborted. Link to file server lost". The file is actually transferred partially, the connection is still open, subsequent transfers run without reconnection. This happens only if TLS 1.3 is used and for this one file, but with multiple different providers.
It transfers well with TLS 1.2 or if no encryption is used, or after re-encoding with a different jpeg quality. Virus scanner and firewall have been ruled out. The questionable file is here:
it has 32.728 bytes (right click and download for testing).
WinSCP version is 5.21.3 GUI commander style on Windows 10 professional
Log file is attached.