PHP files get corrupted

I’ve been having an issue over the past few weeks. For some reason some random PHP files get corrupted as it’s contents is replaced with random stuff, sometimes it appears it’s been partially replaced by a auth.log file. Another time the content was replaced with null-characters 0x00000000. Every time the contents have been replaced the file size have been identical to the original file.

Is this some issue with docker or could it be some issue with the server itself?