What could be causing the encoding problem?

Question

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I welcome everyone.
I ran into a problem with encodings when migrating a local project -> git -> vps
For the second time (so far), there is a problem with encoding. At this particular moment, when authorizing through VK, judging by the debugger, _csrf contains: 2:{i:0;s:5:\"_csrf\";i:1;s:32:\"Jn\0Y][email protected] ?$9;G $51tF\";}'.
It all started with the fact that when authorizing after clicking allow:
Argument 2 passed to yii\httpclient\Client::createResponse() must be of the type array, null given, called in ****/public_html/vendor/yiisoft/yii2 -httpclient/StreamTransport.php on line 73
Starting to dig, I actually saw this cookie in the debugger. This is a first and last name.
All files are in utf8, everything works fine on local. The difference is that it runs on Windows + OpenServer (php 5.6) on local, and on Ubuntu + php 7.1 on VPS. Maybe the question is stupid, but nevertheless Google did not help, maybe I'm not putting the question correctly.
Authorization plugin I use Dektrium's

Answer 1

And again I dug in the wrong direction, having shoveled and debugged everything I could, I remembered. My VPS on the territory of Ukraine with all the consequences and, accordingly, the restriction of access to VK.

Answer 2

Make sure the encoding is UTF-8 without BOM everywhere. And do a post-authorization check in Client::createResponse() like
So that errors do not fall in case of unsuccessful authorization.