After working for a while, pihole is not blocking ads anymore

Yes, but only for 2 of the 4 statements @jfb has posted.
So far, you are missing the output of the following command from the Pi terminal:
nslookup pi.hole 192.168.1.77
And another lookup on a terminal or command prompt from a connected client:
nslookup pi.hole

Based on the info you already posted, you can see that Pi-hole did successfully block 531 of 2,241 or roughly 24% of your DNS queries as undesirable. So from a technical perspective, Pi-hole seems to be working OK.

There could be several reasons why you have the impression you are seeing more ads. e.g. you still could have some stray clients that do not use Pi-hole as DNS server (which the above command from a connected client would reveal), or you are more frequently browsing sites that show ads whose domain is not on any of your blocklists (either because it never was or the site's ad provider changed or a blocklist doesn't include the site any more), or your browser is somehow configured to bypass Pi-hole, etc. etc.

Are you experiencing ads on all clients or specific clients only?
In the latter case, verify that your client indeed uses Pi-hole.

If you are seeing ads on all of your clients, verify as above and then try to find out what domain an ad comes from and whether it's included in your blocklists: