Unlike other Google products, changes to AdSense and the AdSense platform are not all that frequent.
Two of the most impactful changes over the past few years were the introduction of Native Ads (Summer 2017) and Auto Ads (Winter 2018).
Native Ads were launched so that ads on your website would provide visitors a better user experience, and fit in with the look and feel of the site more. Ads are designed in a way to make them look more like they were designed to be placed on the particular page they are being viewed on. It was launched on all device types: desktops, tablets and mobile.
Auto Ads were launched so that publishers could spend less time on managing ads and ad placements and more time on creating great content that is at the heart of websites. Auto Ads uses machine learning to figure out which ads will perform well and where they should be placed on pages. This makes adding AdSense to a site much quicker and easier.
Now, the fact that there are not to many big changes to the platform on a regular basis does not mean that you shouldn’t monitor your AdSense account. You should always be looking at your stats to see how it is performing, particularly if you often make changes to your website. Changes on a page (content, design,…) can have an impact on which ads show on a page, how visitors see ads on the page and whether or not the click on an ad. Keeping aware of what the stats are can help you maximize your AdSense revenue over time.
To keep up to date with any Google AdSense changes, you can always check out their blog at https://blog.google/products/adsense/.