When URL domain/subdomain has literal "dot" text, fang process replaces it with period/dot

[Shbu]

Hello,
I saw below output when I am trying to fang URLs.
In the first scenario, the fanging process converts dot- to literal . giving me wrong output.
In the second scenario, it converts uppercase DOT to literal . giving me wrong output.
For third scenario, the lowercase for the same URL seems to be working fine.

ioc_fanger.fang("http://accounts.dot-star.online")
'http://accounts..star.online'

ioc_fanger.fang("WWW.MDOT.JXCSF.VIP/pay")
'WWW.M..JXCSF.VIP/pay'

ioc_fanger.fang("www.mdot.jxcsf.vip/pay")
'www.mdot.jxcsf.vip/pay'

Could someone help me understand if this is expected? I was hoping the fanging process would give me good URL.