For some reason prints ICMP messages.
Wireshark/TShark dissect the payload of ICMP messages; if they happen to include part of a TCP segment, that will be dissected, so the packet will contain those flags).
How can tell tshark to print only tcp packets?
tshark -n -r ./file.dump -Y "not icmp and (tcp.flags.syn==1 or tcp.flags.ack==1 and tcp.flags.fin==0)"