blocky: Blocky seems to keep query upstream domain via bootstrap DNS even after bootstrapped

As title, I’ve noticed that Blocky seems to keep query upstream domain via bootstrap DNS even after bootstrapped, and it’s frequently, not sure if it’s expected? Thinking about maybe once the query to encrypted DNS upstream is established, should use the encrypted DNS to look up the upstream’s IP addresses?

Here’s the partial of the timestamp records that I observed the query to of upstream encrypted DNS’s domain name. I use only single one upstream in this case, and its TTL of the upstream domain is 300 secs, it looks like the query is much more frequent than the TTL.

15:46:31
15:46:33
15:46:34
15:46:34
15:46:35
15:46:36
15:46:36
15:46:37
15:46:38
15:47:36
15:48:27
15:48:42
15:48:45
15:48:47
15:49:37
15:49:54
15:50:39
15:50:49
15:50:51
15:50:52
15:50:54
15:51:37
15:51:38
15:52:09
15:52:18
15:52:19
15:52:20
15:52:21
15:52:22
15:52:23
15:52:24
15:52:25
15:53:07
15:53:18
15:53:42
15:53:43
15:53:44
15:53:45
15:53:58
15:54:00
15:54:02
15:54:02
15:54:08
15:54:25
15:54:29
15:54:50
15:55:36
15:55:52
15:55:55
15:56:22
15:57:23
15:57:36
15:57:40
15:57:40
15:57:41