htaccess: I need urgent help to remove %3f behind via form submit query generated urls

3 years with hosting at a2hosting. Today I noticed that every form query ends with %3f at the end of the generated url, which makes a 404. This happened suddenly.

This is my htaccess code that works for a years withotu any issue. It remove .php as extension, remove ?check= and replace it with /

# To externally redirect /site.com/foo.php?find=123 to site.com/dir/foo
RewriteCond %{THE_REQUEST} ^GET\s([^.]+)\?check=([^&\s]+) [NC]
RewriteRule ^ %1/%2? [R=301,L]

# To internally forward /site.com/foo.php?find=123 to site.com/dir/foo
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+?)/([^/]+)/?$ $1.php?check=$2 [L,QSA]


# Remove .php extension
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.php [NC,L] 

Code works to change for example query

from
https://www.whatever.org/whatever.php?check=msn.com

to
https://www.whatever.org/whatever/msn.com


Right Now i get 
https://www.whatever.org/whatever/msn.com%3f

I really need to remove %3f

Update.

After playing with htaccess code for some time it seems that this works. Changing

# To externally redirect /example.com/foo.php?find=123 to example.com/dir/foo
RewriteCond %{THE_REQUEST} ^GET\s([^.]+)\?check=([^&\s]+) [NC]
RewriteRule ^ %1/%2? [R=301,L]

to

# To externally redirect /dir/foo.php?find=123 to /dir/foo
RewriteCond %{THE_REQUEST} ^GET\s([^.]+)\?check=([^&\s]+)(?:&(\S+))? [NC] 
RewriteRule ^ %1/%2?%3 [R,L]

solved the issue and %3f behind query generated url is gone.