DNS Hijacking (also known as DNS Poisoning or DNS Redirection) is when a bad actor takes control over a DNS server, allowing them to redirect users to fake versions of the sites they're trying to reach. This threat is bad enough that the FBI published a report on the dangers. Hijacking is also when malware overrides a device's TCP/IP configuration to point to a bad guys DNS server.
Internet Service Providers can also "hijack" your DNS, forcing you to use the provider's DNS servers. I personally change my settings to use Cloudflare's 1.1.1.1 DNS services, completely avoiding my ISP's DNS servers.