Skype dissector gives false positive response on Omron FINS traffic

Describe the bug

I'm trying to write an Omron FINS protocol dissector and for a while I couldn't figure out why it wasn't working as intended. This protocol can use either TCP or UDP, but incorrect detection only occurs when using UDP as a transport. At first I thought it was some kind of logical error in my code (I check almost all header fields to make sure there are no false positives), but then I looked into the skype dissector and saw a lot of kludges.

Expected behavior

Detection as OmronFINS if compiled with my dissector, or as Unknown if compiled without.

Omron FINS packet

Obtained behavior

Invalid detection caused by this

nDPI Environment (please complete the following information):

OS name: Ubuntu
OS version: 23.04
Architecture: x86_64
nDPI version or commit hash: bdb73db1a49d271bfb958eaabcce489013d84f3c
nDPI compilation flags used: --with-pcre2 --with-nbpf-path=~/PF_RING/userland/nbpf/

config.log

How to reproduce the reported bug

Reproducible using ndpiReader?

[x] The reported bug is reproducible using ndpiReader.

If applicable, the used ndpiReader options:

ndpiReader -i ~/omron.pcap

If your bug is reproducible using a pcap, please attach a pcap file (or a valid link to download it)

omron.zip

Steps to reproduce the behavior:

Run 'ndpiReader -i omron.pcap'
See false-positive detection as SkypeTeams_Call

ntop / nDPI