Those reviews don't look very inspiring, not gonna lie. Also, their About page says their service is run from Costa Rica?
Ultimately I don't think these "privacy-first" domain registrars are a great choice, which is a rare thing to say about an internet service.
But you're dealing with private property here and being ICANN-accredited (which Njalla isn't) is kind of important if you're gonna do something serious with your domain. You want those protections that excessive privacy won't permit having.
What's up with everyone in this comment section shilling registrars with abysmal customer reviews? Lol. The only one that even has remotely good reviews is Mythic Beasts.
Anyways, I'd like to recommend IONOS (German). Their service has been flawless so far, and I haven't seen any reports of bad customer either.