Cache problems

Hello,
since a week, I’m having some problems on my website: in particular, sometimes pages appear in an awkward way, just like all of the javascript have crushed.
Please, see screenshot here for mobile and desktop.

If I purge all the caches, the site come back to its standard view.
I have installed W3TC (with just page cache and browser cache modules activated) in addition to Siteground Supercacher: could this problem be related to a kind of conflict between the two plugins?
Please, let me know.
Thank you very much,

https://wordpress.org/plugins/w3-total-cache/