Youtube stopped working for me today when using uBlock Origin in Firefox or Vivaldi with anti-ad enabled.

Ad blockers assert your belief in the web browser as user agent, not server agent

• We know you're using an ad blocker. How dare you.
• Alphabet's cross-subsidy, and the political value of controlling the Overton window, allows Youtube to remain publicly accessible.
• You can get double-penetrated with Youtube Premium, first on the subscription fee then on the usage analytics.