Connection Limit reached on M0 cluster despite killing all possible activity

hi all,
i am having the same issue while using realm on atlas m0,
i built a custom realm function and tested it by clicking on “run” on the realm GUI,
the connection just pops up to 499 and eventually i have no way to decrease the count, the app connection just died and cannot do anything,

i removed all IP list in whitelist and use 0.0.0.0/0 instead, but nothing helps

please any engineer from mongoDB support can help address this issue?
we were planning to move to M10 for the app release but this really makes us to re-consider the technology,
thanks!