This is my first time posting an AppSumo product review. I feel ShortPixel (SP) deserves some credit here, seeing how many previous LTD customers are fast to chastise them.
I know, there is quite a difference between this deal and the previous deal; and on a surface, this deal looks more generous and I understand where the previous customers, myself included, may be coming from. But let us take a moment and think about it…

1. First - SP is a commodity type product. It is not a typical SAAS (like Hey Summit, Storychief, ConvertFox, etc), with many features, plans, etc. ShortPixel‘ credits are used as currency, the closest comparison is DepositPhotos; except, SP’s credits replenish monthly.

2. Last year they offered 5K each month for $29. They only had the ‘local optimization’ option (no CDN). No more no less. Pay $29 one time - get 5k credits each month for LIFE. What’s wrong with that? Could the deal be better if they included 10k? Sure. What about 2.5K? Not so much… This WAS the deal, we accepted it, and we’re using it happily to this day. So far so good.

3. 2019 comes along and they are back to AppSumo, and this time they offer CDN option, PHP  tools, sub-accounts, etc.  
3.1. All new feature except CDN are grandfathered - so if you don’t need extra credits, and you don’t need CDN - you don’t buy this deal and still benefit. 
3.2. But why haven’t they also given CDN to previous customers? We are the ‘founders’ after all!!
Well, CDN is a stand-alone functionality with the stand-alone plugin.
CDN on a large scale is costly.
Not everyone will need CDN. If you‘re a local business, you don‘t need CDN. If you‘re a global business but work with a small number of customers (i.e. your site is not traffic-heavy), you don’t need CDN.
Do you still want the benefits of Adaptive Images plugin? Fine. It is free. Use it with your own CDN. 
Do you still want it with ShortPixel CDN? - OK. get one code of this deal ($39) and you will enjoy 100gb/month for LIFE!
So what is it really about? (and don‘t say it's about ‘company betraying the founders’).
Are you so angry because they want you to pay one-time $39 fee - get EXTRA12K credits/month and 100gb of CDN bandwidth/month - for LIFE? Is it really about $39 bucks? 
One final point about using the CDN/Adaptive Images - please realize that you WILL be using credits monthly, hence the 12k/code with this deal vs. 5k/code during the last deal. Right now most of us are using ShortPixel image optimization in ‘set-it and forget-it’ way. We optimize the image(s) on our/clients’ server once, and they stay optimized forever. With CDN - your images will be stored and served on ShortPixel servers, and they will be ‘refreshed’ and thus use your credits every month. So I would be very selective when using the CDN option. 
 
Conclusion: I don‘t think Short Pixel deserves any criticism - their product works well, and they have honored all past deals. This deal is different - with an option that not everyone will need.