Serious question — China’s latest bomber shows it has no special alien reverse engineering program. Where is China, Russia, etc. in all of this?

For over 20 years, we have only seen copycat aircraft from our supposed greatest rivals. If they had access to advanced technologies this entire time as some theories suggest, why would they be fielding derivative shit like this now? Shouldn’t they be dominating us?

https://nationalinterest.org/blog/buzz/china%E2%80%99s-h-20-bomber-copy-air-force%E2%80%99s-crown-jewel-205205