Technology

It still lasts because there's no easy way YT can offer their own content without the video being available as a file stream (through CDNs at googlevideos subdomains). If they centralize everything to a single, controlled domain (so to allow things as one-time HTTPS request, better session checking and so on), they'd lost the capability of load balancing allowed by the decentralized nature of CDNs. YouTube downloaders (and, by extension, third-party YT frontends such as Invidious) exploit this CDN aspect to download the videos.

It's common to see Invidious instances momentarily blocked. The blockage can't last forever for two reasons: firstly, IPs (especially IPv4) changes due to how ISPs offer IPv4 addresses through CGNAT, so the instance IPv4 (generally domestic servers) will eventually change (often to a completely different IPv4 range) and YouTube won't know that the new IP is a former "offender". Secondly, as IPv4s works through CGNAT, Google can't keep the bans forever because this IPv4 will be eventually rotated to another client from ISP that's completely unrelated and unaware of how their IPv4 was a former address for a downloader. It's like how Signal/WhatsApp/Telegram/Facebook/phone-required services can't really keep a permanent ban for a specific prepaid number (especially on countries like Brazil, where ANATEL allows for phone number rotation when the mobile plan is cancelled), because the number will be potentially owned by another person with nothing to do with the former owner.

So, in summary, Google can either end with YouTube CDNs (ditching their load balancing), or they can try to implement an innovative way to keep load balancing while serving the request one-time only, or they won't be able to do nothing but to perpetually catch themselves drying ice cubes.