I don't think autism gets worse with generations.
I'm diagnosed, as is DS. I was hyperlexic he had significant speech delay is an example of differences but he has the right support to thrive whereas even non-verbal or speech delayed autistics back when I was young where segregated and didn't receive any support other than the questionable ABA therapy, many were put into abusive institutions and this is even more so true of my mums generation and my grans generation. These people would not be reproducing. They would be isolated.
Referring back to DS and I, he isn't more autistic than I am. We are both just as autistic but I was just fortunately born with a combination of traits that fall within the triad of impairments that meant that I could still cope with the limited support tools available to me.
Given we no longer institutionalise our high support needs individuals you will see more of them around compared to previous historic generations (and rightly so, the abuse was abhorrent) but our highest support needs individuals with limited speech and developmental delays and who will need significant daily support for the rest of their lives are still unlikely to have children and therefore you aren't likely to see a positive uptick in autism in the way of support needs decreasing each generation whereas individuals with lower support needs who have lived independently and had the opportunity to form relationships are more likely to have children. Those children will either be autistic or they won't, and if they are then they may also be lower support needs or their support needs will be higher than their parent/s.
I agree with the PP that also pointed out the schooling system these days seems a lot more intense, and we're in the midst of a SEN crisis as there is not adequate support for SEN pupils, which leads to oberwhelm, both over and understimulation and is a curriculum that leaves no room for alternative learning styles. The lack of SEN alternative provision means thst perceptually you're once again more likely to encounter higher needs children to autistic parents in a mainstream setting. Their needs are higher in these settings and not having their needs met creates trauma and trauma leads to dysregulation and this can generate behaviour that may make a child appear "more autistic" but actually they're just more traumatised.
Trauma and autism go hand in hand with eachother.
My assessor who assessed me in April this year said that CPTSD rates are high in autistic individuals, and it's especially the case in late diagnosed autistics as you've spent most of your life not knowing what your needs even are to get them met. It's not exclusive to late diagnosed autistics of course, and as an autism advocate for SEN children, reducing trauma is something that I feel extremely passionate about and making sure schools understand.
So I don't think we get more autistic with each generation. I think we understand autism and how it presents and the triggers of dysregulation more now than ever before but there still isn't the right support or intervention structure in place for our young autistics of today.