Inconsistent, high DNS latency

I've been experiencing sporadic high latencies with DNS lookups using NextDNS over the last few days. This is manifesting as apps sometimes mistakingly thinking that I am not connected to the internet, long buffer times, and overall poor network performance.

I can verify the issue by running a time nslookup command while using the NextDNS servers, and seeing lookups of 10 seconds or longer. Not every lookup takes this long, but many do. Here is an example looking up google.com:

time nslookup google.com
Server: 45.90.30.193
Address: 45.90.30.193#53

Non-authoritative answer:
Name: google.com
Address: 142.251.32.14

nslookup google.com  0.00s user 0.01s system 0% cpu 13.082 total

And another looking up slack.com:

time nslookup slack.com
Server: 45.90.30.193
Address: 45.90.30.193#53

Non-authoritative answer:
Name: slack.com
Address: 3.143.19.65
Name: slack.com
Address: 3.143.53.1
Name: slack.com
Address: 18.221.229.81
Name: slack.com
Address: 18.216.36.190
Name: slack.com
Address: 3.142.111.40
Name: slack.com
Address: 3.129.123.235
Name: slack.com
Address: 3.130.95.182
Name: slack.com
Address: 3.22.139.176
Name: slack.com
Address: 3.134.44.134

nslookup slack.com  0.00s user 0.02s system 0% cpu 13.093 total

Sometime the issue is so bad that the lookup fails entirely:

time nslookup google.com
;; connection timed out; no servers could be reached

nslookup google.com  0.00s user 0.02s system 0% cpu 18.052 total

When forcing another DNS host, such as 8.8.8.8, the issue is not apparent and I always get a response in less than a second:

time nslookup slack.com 8.8.8.8
Server: 8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
Name: slack.com
Address: 18.216.36.190
Name: slack.com
Address: 3.129.123.235
Name: slack.com
Address: 18.221.229.81
Name: slack.com
Address: 3.130.95.182
Name: slack.com
Address: 3.22.139.176
Name: slack.com
Address: 3.143.53.1
Name: slack.com
Address: 3.143.19.65
Name: slack.com
Address: 3.134.44.134
Name: slack.com
Address: 3.142.111.40

nslookup slack.com 8.8.8.8  0.00s user 0.02s system 27% cpu 0.070 total

I tried running the diagnostic tool, but I ran into another issue with the tool itself which prevented the report from being posted.