There’s an option in the plug-in settings to have it remember the fold state:
Remember when a collapsible block is left opened or closed in the webview
that is the setting name, and is described, thus:
If disabled, opening or closing collapsible blocks in the webview will not change their state in the editor, which will cause them to always display as opened or closed, depending on their state in the editor, when a note is reloaded.
In fact, apart from the global setting to remember or not the state of each block when you move away from a note, there is a way to override the chosen default behaviour in particular cases also. This post may may be of interest in that regard: Plugin: Collapsible blocks - #3 by ntczkjfg
HTH