if you dont want to put a sticky ad on the bottom then most of the advice i've read says put it across the fold, so its only partially in view. then it should load straight away and still be on screen when they scroll

If your content is interesting, you can safety put the ad after it. Once people are done reading your content, they are more likely to go elsewhere (click an ad, visit a related page, etc...). If they are focus on the reading , they will skip ads which are in the middle of the content. This is common sense. If you are interested by the content, you are not going to leave the page before finishing the reading, and once you are done reading,
you are not going to scroll up to check the ads ...

Ads in middle of content are performing on page, with poor content, or misleading readers.

As said by @londrum, anchor ads, is a good compromise. Maximum visibility, all the time.

- Above the fold works well for adsense, for reducing core web vitals scores(cumulative layout shift) and for reducing traffic in the process. The later 2 aren't good so use wisely.

Question, how do you know your top ad is not just under the header above all content? Do you have auto ads turned off? If not adsense will toss ads up there and though you can block up to 10 ad slots the one just under the header is near imposible to find and block in your ad settings preview. Sometimes you can see it sneaking up there in the pagespeed screenshot.

Also, about core web vitals, the score doesn't represent any one page. Your pages are grouped and averaged so reports to any page in the group affects all pages in the group, including the one you looked up. You can find grouped pages in your search console. Consider removing ad code from pages in the group that get little traffic, the least they can do is improve overall site metrics. YMMV.

<?php if (is_single('50')) echo ' AUTO ADS CODE HERE ';?>

If you place that in your header template file for your wordpress theme it will insert your ad code only on post 50. You can ad multiple pages by adding a coma after the 50 and every other post number you include. You can also add multiple conditions like is_page, is_home etc. You can find the post number in your wordpress dashboard, in the posts section click view all and find the post you want to monetize, the post number is part of the link to the post, hover over it to see the number.

In your adsense settings turn off in-page ads and turn on the anchor ads(but not the widescreen). Next create a vertical display ad and place it in sidebar 2. In wordpress you can create multiple sidebars so use sidebar 1 sitewide and sidebar 2 only on pages you want ads in, like post 50. Use the html widget to hold the code.

The result, ads only on desired pages with an above the fold ad on desktop(in sidebar) and an above the fold ad in mobile(anchor ad). Though above the fold both these ads have little core web vitals impact other than how slow Google is. The anchor ad only appears when a scroll is detected and the sidebar ad code is technicaly at the bottom of the main content. It doesn't block.

Manually place more ads on that post via manual ad units if you wish, the end result is most pages are fast with no ad code and the most trafficked posts are monetized.

It's the best tradeoff you'll find in the war between pagespeed and adsense, IMO. Good luck!

Edit - if your most trafficked page has very low CPMs make sure you A/B test some lesser trafficked pages. If a page pays 10x more but only gets 10% of the traffic it pays the same as the more popular page. Slow code affects fewer people overall, a good thing.

/ends ramble /hopes he gave you some ideas

Another option in a "mobile first" world, for wordpress sites, is to make use of the wp_is_mobile core wordpress mobile detection. [developer.wordpress.org...]

Wherever you insert your ad code wrap it in a mobile check to serve it ONLY to desktop users.

Then find an alternative to adsense that is faster on mobile. The code would look something like...

<?php if (!wp_is_mobile()) { ?> YOUR AD CODE HERE - FOR DESKTOP ONLY<?php } ?>

or

<?php if (wp_is_mobile()) { ?> YOUR AD CODE HERE - FOR MOBILE ONLY<?php } ?>