I had also the same issue. I found a hack to disable the PTR DNS lookups.
I installed this addon in HA.
https://github.com/tronikos/default_config_disabler
Then from the configuration of the addon, I just disabled the dhcp
This stopped all the PTR DNS lookups.
Just to add that I installed homeassistant for the first time in a docker container a few months back.
Later I noticed that I was having strange DNS resolution failures. Turns out I was being blocked by quad9 DNS because HA was doing a PTR query for each IP in the local address range, exactly once an hour, all within a few milliseconds.
Too bad this is still not fixed by default after all these years.
This worked for me. Thanks so much. If I want to have HA auto-discover new integrations I can easily enable and then disable dhcp from this integration.