Site has stopped being properly responsive

www.cpaviation.com/

When I rebuilt the template 2 years ago, and since, the site was fine. Something has happened (quite likely something I added!! I thought it was changing to PHP8 but I changed back to 7.4 but nothing changed).

However, it's displaying strangely in mobile - the right side is being cut off. Not sure what's happening. If you have some quick advice it would be appreciated. I'm going to be rebuilding in J!4, but I don't want to have to rush preferably.

Hi
after checking,the problem comes from the button "take flight today"
white-space:nowrap on the .btn class is the reason why you got this problem, it can not break on 2 lines and the text is longer than the column size >> goes outside of the page

nothing to do with page builder ck at all ...
CEd

Actually, that shouldn't be an issue. I just noticed that whole panel, plus other ones below, are meant to stack in mobile view, but are not. It's like I've added some code to tell the site to display everything as desktop, but to cut off anything that doesn't fit.

Actually, that shouldn't be an issue.

I have given you my point of view after inspecting the code of your page to answer your initial request, but if you think that this is not a problem, then ok