Example: https://youtu.be/wAkV_fWOMFU
Then there is Dahua, which is basically Hikvision Junior. Reolink is somewhat in the middle, in the past they have OEM'd products from Dahua, and others. It can be difficult to know who actually manufactures a lot of the Chinese surveillance cameras, as the companies often go to great lengths to obscure the details.
Initially it was completely locked down, but I discovered the cameras eventually refuse connections after their RTC drifts too much. I could not get them to use my router for NTP because they preferred pool.ntp.org. I had to open up that port as well as allow them to make DNS lookups on my router.
They have been working fine with that minimal amount of internet access, but curiously, the firewall logs show frequent blocked connections to Reolink IPs on port 9999.
If you have Reolink cameras, your network is open, and you're worried about data exfiltration, then 9999 is one port you may want to block.
then you need not open them up to anything :)