Is the 40% increase region-specific? I'm a YT Premium subscriber and they just had a price increase in the US three months ago ($120 to $140 yearly, similarly billed monthly).
I recognize this doesn't solve your reasons at all, but for anyone facing an un-grandfathering who is simply price-conscious, if you're willing to commit for a year to YT Premium, it's effectively $11.66/mo.
I just squeaked into pre-increase Nest pricing for the final year I'll use it. This has been a big year for 40%+ subscription price increases, Google and otherwise, it seems.