WP blocks the update/add new custom field with "onClick='this.select();"

[OpossumPetya]

Tried to add bookmarklet code to the post, but WP now blocks the update/add new custom field when there's JS events(?), error 403 in browser console:

<a href="javascript:(function(){var%20t=location.protocol+$(%22img[class*='postcard-image']%22).attr(%22src%22);$(%22img[class*='postcard-image']%22).after(%22%3Cp%3E%3Cbr/%3E%3Cinput%20type='text'%20style='width:500px'%20onClick='this.select();'%20value='%22+t+%22'%20/%3E%3C/p%3E%22)})();">Postcard Image Address</a>

Once I removed onClick='this.select(); it was accepted.

Edit:
WordPress - 5.2.3
Code Embed - 2.3.2

[OpossumPetya]

It's probably not plugin's fault, but just FYI.
Also, it wasn't happening before (though, probably last time I was updating this bookmarklet was at least a year ago).

[dartiss]

Thanks for letting me know - I'll take a look into it 👍🏼