phpcs --standard=DrupalPractice shows the following report.
FILE: tests/src/Functional/FontYourFaceInstallTest.php
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FOUND 0 ERRORS AND 5 WARNINGS AFFECTING 5 LINES
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54 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
58 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
62 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
66 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
67 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
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FILE: tests/src/Functional/FontYourFaceSubmoduleInstallTest.php
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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52 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
53 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
67 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
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FILE: tests/src/Functional/FontYourFaceLocalFontInstallTest.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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52 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
54 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t()
| | instead
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FILE: modules/local_fonts/src/Form/LocalFontConfigEntityForm.php
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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131 | WARNING | File::load calls should be avoided in classes, use dependency injection instead
139 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
145 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
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FILE: src/Form/FontForm.php
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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21 | WARNING | Unused variable $entity.
35 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
41 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
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FILE: src/Form/FontDisplayForm.php
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FOUND 0 ERRORS AND 4 WARNINGS AFFECTING 4 LINES
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46 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
56 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
173 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
179 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
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FILE: src/Form/FontSettingsForm.php
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FOUND 0 ERRORS AND 5 WARNINGS AFFECTING 5 LINES
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57 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
83 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
86 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
123 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
138 | WARNING | Unused variable $config.
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FILE: src/Controller/FontYourFaceController.php
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FOUND 0 ERRORS AND 6 WARNINGS AFFECTING 6 LINES
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28 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
45 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
58 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
75 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
92 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
105 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
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FILE: src/Plugin/views/filter/FontYourFaceStyleFilter.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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55 | WARNING | Unused variable $exposed.
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FILE: src/Plugin/views/filter/FontYourFaceProviderFilter.php
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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44 | WARNING | Unused variable $name.
47 | WARNING | Unused variable $name.
59 | WARNING | Unused variable $exposed.
-----------------------------------
FILE: src/Plugin/views/filter/FontYourFaceWeightFilter.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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62 | WARNING | Unused variable $exposed.
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Those files need to be changed to fix the reported issues