If I use Lattice path effect on any path, it keeps distorting every shape even when no path effects are not used on them!
Am I doing something wrong? Is there a way to stop it?

Here's a short gif showing the issue, you can notice that there is no path effect applied:
https://imgur.com/IxpFnml

I am using Inkscape 1.0 64bit on Windows 10. 

Here's the gif in case there's some difficulty seeing it on imgur. 

That's messed up. 

I'd try relaunching Inkscape.

If that doesn't help, I'd reset the preferences and relaunch Inkscape.

Relaunching didn't help but resetting the pref. did.
Thank you!!

I'd keep my eye on it. That should never happen under normal operation. If it does, it would be very helpful to know a way to reproduce the problem and file a bug report.