I don't know if YouTube has done something on their end, or something went REALLY wrong with the latest update, but if I have SponsorBlock enabled, YouTube will now refuse to load anything but my subscriptions page.
It's also become exceptionally hit or miss with catching sponsored content, even when I manually tag stuff.

Edit: I re-enabled it with all other addons turned off, and it still did this, and it it was only when I turned it off when YouTube would load anything but my subscriptions page as of 9-8-2025.