Dongwon Cho, the '8.0.19/stable' charm tag is broken by design (see reply to my Bug #2004046). As mentioned above, only the deb package versions can be trusted here. For focal, ensure your mysql-router deb package is 8.0.32-0ubuntu0.20.04.2 (which is in the 'security' repo and may not have had time to propagate to your local mirror at the time of your test).
Dongwon Cho, the '8.0.19/stable' charm tag is broken by design (see reply to my Bug #2004046). As mentioned above, only the deb package versions can be trusted here. For focal, ensure your mysql-router deb package is 8.0.32- 0ubuntu0. 20.04.2 (which is in the 'security' repo and may not have had time to propagate to your local mirror at the time of your test).