Logstash, ELB access logs, client port displays with a comma

Hi, I'm using logstash for parsing AWS ELB access logs, and noticed that client port displays with a comma in Kibana
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but in JSON tab it displays correctly, could you please explain, why it happens? , thanks

"backend_response": 200,
"clientport": 50103,

I think that is just the default numeric field formatter.

thanks for help!
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