'clear' command will block 'CTRL+L'

1. Connect to my KUbuntu 20.04 with SSH, CTRL+L first time can clear the screen, but the contents will appear when I press any keys, then, 'CTRL+L' cannot work.
2. Connect to my kubuntu with SSH, then duplicate the session, the CTRL+L work fine unitl I clear screen with 'clear' command. then the issue the same as the point 1.

My KUbuntu 20.04 Info:
my default shell is 'bash'

Reproduce the report in WindTerm using an SSH connection to Kubuntu 20.04 with bash: compare CTRL+L before and after running the clear command, including a duplicated session. Trace the terminal input and screen-clearing behavior involved in that sequence; done means CTRL+L continues to clear the screen after clear has run.

Written by the indexing model from the issue text.