It’s hard to tell, because I can’t see that search bar on the page anymore. My guess would be that if you use any cache, that might need clearing, including page, asset, CDN or anything you have. Jumping a PHP version should not be a problem, as it’s backwards compatible with previous PHP versions (aside from some very rare features).
Also, make sure that the custom CSS codes are still there, they might have been removed for some reason.Best,
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