I've head Netbird running for the last few months... In general it works quite well, but it would keep messing with my dns-resolving, and I couldn't find the setting to stop it inserting itself into my resolv.conf.
During the last few weeks I've removed netbird from all my systems (about 12), mostly because of issues on laptops where resolving or networking would break after they moved to a different network/location.
Just for future reference, you can disable DNS management for specific groups [0].
You can find the option under "DNS > DNS Settings > Disable DNS management for these groups". Netbird will stop modifying the resolv.conf on those groups.
Can Netbird run the DNS resolver (so it can be used for the internal domain ONLY by systemd-resolved) but not alter the host's DNS settings?
It looks to me like the setting that tells Netbird to leave the system DNS alone is arbitrarily tied to the setting that causes it to run a resolver at all.
During the last few weeks I've removed netbird from all my systems (about 12), mostly because of issues on laptops where resolving or networking would break after they moved to a different network/location.