Did you actually complete the VCP-DCV 2021? You say you passed the 2V0-21.20 exam, but did you ALSO complete authorised vSphere training?
If so, the path which applies to you on the page you linked to is "VCP-DCV 2020 or Newer", for which there is only 1 hard requirement which is passing an exam - you cannot attempt the 2V0-21.20 exam again, so would have to pass the new 2V0-21.23 exam on vSphere 8.x.
Updating your VCP by ONLY completing authorised training only applies to holders of VCP-DCV 2022.
Strangely, if you had NOT completed the VCP-DCV 2021 (as per my opening question) then the combination of passing the 2V0-21.20 exam and completing the authorised vSphere v8 course WOULD mean that you'd met the hard requirements of VCP-DCV 2023, since the path on the page you linked to which would apply is "no VCP certifications".
I hope that makes sense to you.