PDF file randomly breaks upon upload on WordPress

The issue randomly started happening. When I upload a PDF file via the media library, it sometimes ‘adds’ random lines and graphics to the PDF file(or solid brown color), but sometimes it is okay. Managed WP core is updated to the latest, plugins as well, PHP is running 7.3. I wonder if it is ever a WordPress issue or a hosting issue.

What could be the reason?

here’s the list of the plugins:

Abandoned Cart Lite for WooCommerce
Advanced Custom Fields PRO
Advanced Order Export For WooCommerce
Contact Form 7
LionScripts: IP Blocker Lite
Mouseflow for WordPress
MultiLine files for Contact Form 7
Really Simple SSL
SVG Support
WooCommerce Order Status Control
WooCommerce Order Status Manager
WooCommerce Stripe Gateway
WP Cerber Security, Antispam & Malware Scan
Yoast SEO Premium

Which one has a chance to be the problem?

here’s what the broken PDF looks like(only one of the pages, other ones are fine actually:


Also, the XHR Request sometimes responds with JSON data, and sometimes the response is empty. This is all RANDOM, i.e. it happens on every 2nd or third upload(through the ACF File field), a very weird bug.

EDIT: I have found it is not inserting _wp_attachment_metadata in the wp_postmeta table(it works only through media library, but not from the ACF file field)

EDIT 2: Just found out it breaks png and jpg images on upload too

EDIT 3: It does the same thing on blank WP installation on the BASIC media upload