The deploy command uses clack's spinner to print the upload progress for files. When running the command in a non-interactive environment the output still contains ANSI escape sequences used to clear the line, producing output like the following where all spinner updates are joined into a single line:
�[?25l│
�[999D�[J◒ 3 / 3 uploading example-report.html�[999D�[J◐ 3 / 3 uploading example-report.html�[999D�[J◓ 3 / 3 uploading example-report.html�[999D�[J◑ 3 / 3 uploading example-report.html�[999D�[J◒ 3 / 3 uploading example-report.html�[999D�[J◐ 3 / 3 uploading example-report.html�[999D�[J◓ 3 / 3 uploading example-report.html�[999D�[J◑ 3 / 3 uploading example-report.html�[999D�[J◇ 3 uploaded, 49 unchanged, 52 total.
�[?25hUploading build manifest... {
In most cases the output will also print color codes like [35m◒�[39m.
Related: #1446