For example, see the .audio domain or any of the other Uniregistry domains that went through a massive as much as 1400% price increase in 2017 after people had already bought domains. https://blog.dnsimple.com/2017/08/uniregistry-tld-price-incr...

It caused quite a stir. I luckily was able to get grandfathered pricing for a .audio domain through my registrar (namecheap). Although their system did fail at one point and charged me the non-grandfathered price at one point, and I had to go to support for a refund. What a headache