If the price of forum.dev is indeed $850 then the attached TRY 13040 invoice implies USD/TRY 15.34 which was last seen in May. The $12 domains go for TRY 75 which implies USD/TRY is 6.25, last seen in 2020.
It looks to me that the prices in TRY are simply set by hand and not refreshed that often. OP got a nice deal via such manually set price in 2021 and that's all that is going on here.
Disclaimer: I work at Google but I have absolutely nothing to do with domains or forex rates.
The wholesale price is determined by the registry (Google), but the retail price will include markup from the registrar (Namecheap, Porkbun, Google). In the case of .dev Google runs the registry and acts as a registrar. As for registrars, that comparable (6b.dev) is $709 at Porkbun, $720 at Google, and $843 at Namecheap.
Namecheap is marking it up more than the other registrars.
I wonder if your registration last year included any kind of first year discount. This is the first time I've seen someone show an actual receipt for this type of complaint. I estimated the pricing at about $315USD vs $700USD. That's enough of an increase that I'm really curious to know what happened.
I also contacted another domain registration service to verify this price. They said that the domain transfer fee is $843 and that they have nothing to do with it, the pricing is determined by registrar(Google in this case).
Attached: https://twitter.com/EmirKarsiyakali/status/16014456975341649...
Even while writing this comment, they also responded from their own Twitter: https://twitter.com/Namecheap/status/1601447984775962625