Font size has nothing to do with paragraph counting.
Not sure what the problem is.
Please enable remote debugging and clearly describe the issue you have, maybe with some screenshot.
https://wordpress.org/support/topic/ad-inserter-support-before-you-ask-for-help/
I already tested it. It is not happen with every theme, but on my 2 website has this problem. I just found this problem today. So if I use this text, everything is fine: https://i.imgur.com/uZtMOiN.png If I use this text, it will change every paragraph in the post: https://i.imgur.com/RGUQRDg.png
This is my website: harmonikum.co
2 example:
So this is ok: https://harmonikum.co/ahogy-osszekulcsolod-az-ujjaid-megmutatja-hogy-milyen-ember-vagy/
This is not good: https://harmonikum.co/15-tortenelmi-fenykep-amely-feltarja-a-tortenelem-kimeletlen-oldalat/
Remote debugging doesn’t seem to be enabled.
Please check – you also need to disable caching.
I tried everything, but the figures are the same.
Also I do not understand but I tried even bigger text, and there was no ads in the post. So it is the plugin.
I’m sorry but remote debugging still doesn’t seem to be enabled.
I just enabled it, but there is no changing.
Of course, but at least I can now check the blocks.
On both pages the blocks are inserted according to the settings.
Block 1 is inserted after 2nd paragraph, block 2 after 6th paragraph, etc.
Of course, the paragraphs are different and you have h3 headers between them.
Can you please clarify what issue do you have?