Daily service outage

For about 2 months I'm experiencing nearly daily outage (I have grafana monitoring if exact timestamps are needed) of service which happens in the evening. Last occurrence happened between 19:36 and 19:49 CET today. At that time I can observe following warnings in the log:

Endpoint failed: https://dns1.nextdns.io#45.90.28.0,2a07:a8c0::: roundtrip: context deadline exceeded
Endpoint failed: https://dns2.nextdns.io#45.90.30.0,2a07:a8c1::: roundtrip: context deadline exceeded

and every request ends with

doh resolve: context deadline exceeded

At that time both endpoints 45.90.28.0 and 45.90.30.0 don't respond to ping. Tracepath ends at some CDN server (root cause?):

$ tracepath 45.90.28.0
1?: [LOCALHOST]                      pmtu 1500
 1:  <local>                                     0.559ms
 1:  <local>                                     0.412ms
 2:  <router>                                               1.745ms
 3:  no reply
 4:  <ip>.infra.chello.pl                          14.554ms
 5:  no reply
 6:  pl-waw26b-ri1-ae-3-0.aorta.net                       18.690ms
 7:  war-b4-link.ip.twelve99.net                          15.752ms
 8:  war-b3-link.ip.twelve99.net                          16.285ms asymm  7
 9:  datacamp-ic-355850.ip.twelve99-cust.net              15.797ms asymm  7
10:  unn-156-146-32-237.cdn77.com                         13.748ms asymm  8
11:  no reply
12:  no reply
...
30:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500

Sometimes during outage service re-appears at short intervals and then ping.nextdns.io shows me this:

■ anexia-waw                25 ms  (anycast2, ultralow2)
  edis-vno                  40 ms
  zepto-ber                 42 ms
  anexia-prg                43 ms
  anexia-bts                47 ms
  anexia-bud                50 ms
  enahost-bts               51 ms
  hostens-vno               54 ms
  zepto-prg                 55 ms
  zepto-waw                 error
  anycast.dns1.nextdns.io   error  (anycast1)
  dns1.nextdns.io           error  (ultralow1)