resolvectl statistics returns 0

I use Ubuntu 22.04.

My DNS requests take more than 10 sec. If I reload my Firefox page, the DNS resolutions remain the same: my DNS resolve the query, but it takes a lot of time.

If I run in a terminal the following command after loading a web page, I get the following output:

    resolvectl statistics
DNSSEC supported by current servers: no

Transactions            
Current Transactions: 0
  Total Transactions: 6
                        
Cache                   
  Current Cache Size: 0
          Cache Hits: 0
        Cache Misses: 0
                        
DNSSEC Verdicts         
              Secure: 0
            Insecure: 0
               Bogus: 0
       Indeterminate: 0

resolvectl seems working:

resolvectl query google.fr
google.fr: 142.250.65.163                      -- link: wlp0s
           2607:f8b0:4006:820::2003            -- link: wlp0s

-- Information acquired via protocol DNS in 1.6251s.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: network

resolvectl query google.fr
google.fr: 142.250.65.163                      -- link: wlp0s
           2607:f8b0:4006:820::2003            -- link: wlp0s

-- Information acquired via protocol DNS in 1.1ms.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no
-- Data from: cache

But it seems not used (by Firefox?) Seems it concerns also other apps than Firefox (slack for example).

So I'm not sure my DNS resolution works fine.

Should I expect all DNS requests to use resolvectl? Any idea how I could solve this DNS resolution problem?

Maybe it's related, but recently I ran a chown $USER:www-data /. I tried to fix it, it almost works, but maybe there is something remaining to fix?

Thanks for any help you could provide.

Maybe it came from these custom DNS I use: when switching to other ones, every is back to normal. Don't know if this is my ISP who blocks these DNS or if it comes from the DNS themselves, but everything is back to normal.