So here is an odd issue, form checkboxes flicker in and out of visibility on Mac. I tested this on Windows and no such issue occurs.
Visit a site with a checkbox on Mac. For example:
https://www.w3schools.com/tags/tryit.asp?filename=tryhtml5_input_type_checkbox
https://getbootstrap.com/docs/4.0/components/forms/#checkboxes-and-radios
Click on the Checkbox
This is a video recorded on the w3 page listed above going over checkboxes.
https://streamable.com/dfry4
Checkboxes should not flicker in and out of visibility
100% of the time
Brave | 0.55.3 Chromium: 70.0.3538.12 (Official Build) dev (64-bit)
Revision | ad61584ca32115f953ce656dd75b44f1c502a75d-refs/branch-heads/3538@{#179}
This does not occur on the laptop version of brave
This does not occur on chromium. It occurs in Brave with no extensions installed and with brave shield off.
Seeing this as well on the same version of Brave Dev on Mac as @andrewcking. Not just on one website, on multiple websites, and happens with Shields both on and off.
I recorded a quick GIF of the behavior:

This is actually happening not just for checkboxes but also radio buttons:

Which version of macOS is this? Reminds me of brave/browser-laptop#14348 (problem with macOS 10.14 Mojave).
I’m able to reproduce on both my work laptop (High Sierra) and my personal laptop (Mojave public beta).
55.5 fixed this for me (Mac - High Sierra)
Edit - No still broken but seems to be intermittent
Thanks for the suggestion @andrewcking. Glad that fixed it for you. Unfortunately for me it's still broken on 0.55.5:

If anyone is having trouble reproducing, I see it pretty reliably on StickerMule's site (although this is not the _only_ site where it manifests).
Also note that I tried clearing all browser data from Brave as well as a (relatively nuclear) manual option:
sudo find ~/Library -iname '*brave*' -delete
Let me know if there's stuff outside of ~/Library I should try as well.
I played around with it again and I was able to get some radio buttons to disappear on me - so my earlier statement may have just been one of poor timing. Yep, still broken.
OK, I think I may have narrowed the issue down to something possibly useful. Turing Hardware acceleration off fixes the problem for me:

Found this after some digging on Google / StackOverflow. @andrewcking – want to give this a try and see if it works for you as well?
Possibly related to #1151 I also recently filed.
A similar issue was reported on browser-laptop with https://github.com/brave/browser-laptop/issues/14348
User @hansemannn shared an extension they made which works around the issue:
It's interesting to see the fix was to change the zoom level for the page. I reproduced the problem using brave-core on my mac and verified that increasing the zoom level does cause the checkbox / option boxes to render properly. Hopefully this provides a hint to where the problem is 😄
and verified that increasing the zoom level does cause the checkbox / option boxes to render properly
fyi, what i always do when this problem occurs is quickly hit CMD + Tab twice (switch to another window and back), which also fixes it
@bsclifton Do you have hardware acceleration on? https://github.com/brave/brave-browser/issues/1160#issuecomment-423028344 says turning it off fixed the issue.
I can reproduce as well. Disabling hardware acceleration fixes the issue.
https://streamable.com/zjlha
macOS High Sierra 10.13.6
Version 0.55.10 Chromium: 70.0.3538.22 (Official Build) beta (64-bit)
+1 from @sundarms via #1355 for radio buttons not being rendered
Verified passed with macOS 10.12.6 x64
Brave | 0.55.12 Chromium: 70.0.3538.45Â (Official Build)Â beta(64-bit)
-- | --
Revision | cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS | Mac OS X
Went through verification using the following build under macOS 10.13.6 x64 - PASSED
Brave | 0.55.12 Chromium: 70.0.3538.45Â (Official Build)Â beta(64-bit)
-- | --
Revision | cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS | Mac OS X
Most helpful comment
OK, I think I may have narrowed the issue down to something possibly useful. Turing Hardware acceleration off fixes the problem for me:
Found this after some digging on Google / StackOverflow. @andrewcking – want to give this a try and see if it works for you as well?
Possibly related to #1151 I also recently filed.