NextDNS + Proton VPN connection issue

My issue: I can't connect NextDNS and Proton VPN at the same time (device-wide). I suspect it's a DNS misconfiguration on my end, user error.

Details: It worked pretty well a few months ago but it stopped working  month ago-ish. When I have Next DNS connected and I turn on Proton VPN, the VPN says connected. However, I can't load anything in my browsers. Brave gives me the following error:  "DNS address could not be found. Diagnosing the problem. DNS_PROBE_POSSIBLE".

My setup:

• Linux - Zorin OS
• I use the recommended "systemd-resolved" to connect NextDNS for Linux in the file called "resolved.conf"
• [Resolve]
  DNS=45.90.28.0#______.dns.nextdns.io
  DNS=2a07:a8c0::#______.dns.nextdns.io
  DNS=45.90.30.0#______.dns.nextdns.io
  DNS=2a07:a8c1::#______.dns.nextdns.io
  DNSOverTLS=yes
• I run the Proton VPN app with a free VPN plan

What I have tried:

• Waiting 5 minutes
• Uninstalling + reinstalling Proton VPN
• Multiple system restarts
• Removing + adding the configuration script under "resolved.conf"
• Changing the VPN connection protocol (Wireguard and OpenVPN)
• Disabeling IPv6 in the VPN
• Connecting to different VPN endpoints