You have a configuration problem. The wlan0 interface is at one IP, and Pi-hole is configured for a different IP (not even on the same range).
*** [ DIAGNOSING ]: Network routing table
default via 192.168.1.1 dev wlan0
192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.106
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] inpost-polska-car.orders091.info is 0.0.0.0 on lo (127.0.0.1)
[✓] inpost-polska-car.orders091.info is 0.0.0.0 on wlan0 (192.168.1.106)
[✓] doubleclick.com is 172.217.13.174 via a remote, public DNS server (8.8.8.8)
*** [ DIAGNOSING ]: Setup variables
...
PIHOLE_INTERFACE=wlan0
IPV4_ADDRESS=192.168.0.18/24
First, ensure that your IP on the wlan0 is static on the Pi. This is usually set in file /etc/dhcpcd.conf.
Second, run pihole -r and select the reconfigure option to set up Pi-hole on the correct IP.
Your DHCP server is passing out Cloudflare as DNS in addition to your local DNS server. This allows clients to bypass Pi-hole at any time. Remove the Cloudflare entry.
*** [ DIAGNOSING ]: Discovering active DHCP servers (takes 10 seconds)
Scanning all your interfaces for DHCP servers
Timeout: 10 seconds
* Received 548 bytes from wlan0:192.168.1.1
Offered IP address: 192.168.1.106
Server IP address: N/A
Relay-agent IP address: N/A
BOOTP server: (empty)
BOOTP file: (empty)
DHCP options:
Message type: DHCPOFFER (2)
server-identifier: 192.168.1.1
lease-time: Infinite
netmask: 255.255.255.0
router: 192.168.1.1
dns-server: 192.168.1.106
dns-server: 1.1.1.1
--- end of options ---
DHCP packets received on interface wlan0: 1
DHCP packets received on interface lo: 0
Other observations from your debug log:
This regex entry will not be effective, because http is not part of a domain name (it is part of a URL).
(\.|^)http://get-express-vpn\.online$
Two of your subscribed adlists do not appear to be available on the internet any longer:
[i] Target: https://mirror1.malwaredomains.com/files/justdomains
[✗] Status: Not found
[✗] List download failed: no cached list available
...
[i] Target: https://hosts-file.net/ad_servers.txt
[✗] Status: Not found
[✗] List download failed: no cached list available
It seems when there's a certain number of requests coming in, pi-hole will drop network connectivity, process those requests then resume network connectivity.