Hello,
this is console output in page edit with wysiwyg editor custom fields:
This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”. post.php
JQMIGRATE: Migrate is installed, version 3.3.2 load-scripts.php:5:709
MouseEvent.mozPressure is deprecated. Use PointerEvent.pressure instead. 2 wp-tinymce.js:3:8856
Nothing else appears there even during custom fields editing.
I have the same problem:
WP 5.6 (clean install or with plugins – doesn’t matter)
ACF PRO 5.9.4
FF 85.0 (64 bit) on OSX 10.14.6
Flushing cache doesn’t work in my case.