Hi, I reported this problem a year ago and it still hasn't been fixed, although they boast on their blog that JA Blockk is "Full compatibility with Joomla 5.3".
https://www.joomlart.com/forums/d/50146-ja-blockk-212-visual-issues-and-mobile-menus
In response, I received a partial prosthesis for the problem that the developers made when changing version 2.0.4 to 2.1.2. It was in this update that a large part of the css / scss code was broken or removed from the files.
I still use version 2.0.4 on my website and I'm on Joomla 4. I'm waiting to update Joomla to version 5. I hope to see a 100% fixed version of JA Blockk.
I'm still waiting for JA Blockk to be professionally fixed by the Developers, then I'll renew my subscription.
The css / scss source code needs fixing, because there's a lot of copy / paste from other templates.