Hello,
Thanks for reporting the compatibility problem. Currently, 5.1.5 is the latest version. The issue has been reported to the developers.
For confirmation, the error reported by the tools is:
FILE: /wp-cloudflare-page-cache/src/Modules/Assets_Manager.php
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FOUND 1 ERROR AFFECTING 1 LINE
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362 | ERROR | Indirect access to variables, properties and methods will be evaluated strictly in left-to-right
| | order since PHP 7.0. Use curly braces to remove ambiguity.
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