Multiple file uploads fail with tor browser 14.0.x

There seems to be an issue with multiple file uploads that accept multiple files each on mobile tor browser versions 14.0.x. Using 13.x.x version, browser files are correctly uploaded, but with 14.0.x, the server receives only a few of the selected files, and some of them are "Partially uploaded" (php backend; it is one of the default upload errors). 

Tried to upload images; each image is about 100-600 kB. Issues start with about 4 inputs, 3 files each. Everything works fine on desktop browser (even newer versions).

The basic example (html):

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