Hi. I work on Google Registry. forum.dev is and always has been a premium domain name (and you paid that same premium price at initial registration). We price some domain names higher than others to help prevent cybersquatting, so that desirable domain names remain available for legitimate registrants rather than being sold for extravagant sums on the after-market. We have never increased the price of a single domain name after registration in our entire decade of existence.
For another example of a premium domain name that is still available for registration (in case people here want to verify the user experience), perform a domain name search for money.dev at your registrar of choice. It will be clearly marked with its yearly premium price. You would have seen this same information when you initially registered forum.dev.
For another example of a premium domain name that is still available for registration (in case people here want to verify the user experience), perform a domain name search for money.dev at your registrar of choice. It will be clearly marked with its yearly premium price. You would have seen this same information when you initially registered forum.dev.