I have found that the ability to mask requires a LOT of effort - and as you get older, you simply don't have the physical stamina to keep it up - and as the world gets infinitely more complex and stressful as you get older, the challenges of the mask get too much to keep up.
So yes, in my experience, people become 'more obviously' autistic because they just can't hide it as efficiently as they age. It's what leads to most late-diagnosis scenarios. I made it to 42 before my Asperger's was too obvious to hide. I'm not 'more autistic' - but I appear more autistic because of my failing mask.
