Blocking the clipboard contents is actually a deliberate security feature on many sites. It prevents simple scripts from brute-forcing their way through verification attempts. It prevents spyware from lifting the contents of the clipboard for their own uses. It prevents malware from injecting invalid inputs (and overflow attacks) into the 2FA fields.
If it is too frustrating to operate then you do have the option of turning it off.
I commend people for giving PM feedback on details like this. You never know, maybe PM is still focussed on getting things right (so they can finally feel confident that they're getting their money while letting the thing run on autopilot). Most of the other recent improvements on Self-Serve are customer requests (or demands) which have been frequently mentioned ... even if some of the specific improvements took most of a decade to arrive.
