I’ve read the FAQ and Guidelines, and by your wording and the posts tag I suppose this is a “hack tweak” with no configurable options in settings
This either no longer works with the latest lastpass or does not provide the premium feature of unlimited “device switches”.
If people aren’t having this problem it could be it doesn’t work if you have already used up your device switches like I have.
All I can say is it doesn’t work at providing unlimited device switches on an iPhone 12 running iOS 14.x on the latest version of LastPass.
EDIT for dev: version 5.0.0 breaks it as will all future versions.
Temp solution for USERS: I’d use AppStore++ (free) and use it to downgrade to a mid to late version 4.xx. After doing that just run the .deb file using the same instructions above.