Word salad injected in the header of every single plugin PHP file – help! D:

Hi,

I attempted to install WpBackup on a client site and immediately all my plugins stopped working due to invalid headers. I deleted WPBackup and reset the plugins folder but every single plugin file now has an additional PHP tag with garbled code in it like this injected at the start of the file before the ‘real’ opening PHP tag:
[Redacted]

I am going through and removing all of these manually. Please tell me there is a faster way to do this (I am not a database expert but am hoping there might be a query that could solve it), I don’t know what to do.