No, what there has been is an increase in an already prevalent phenomenon (see: mass shooters) of blaming mental illness and/or personality disorders for abusive, violent, and flat out fascistic actions, when they don't actually cause those, it's just so much easier to do than to think more deeply and/or critically about the systems and structures that don't only enable, but encourage such behaviour, especially in those with privilege and power (because actually mentally ill people are much more likely to be victims of violence and other abuse, than perpetrate it).

Using diagnosable conditions as shorthand for "abusive" or "toxic" or "harmful" or "violent" or "racist" or whatever else, is ableism. It deepens already existing and harmful stigmas, prevents people from seeking help and support and being open about their struggles, and actually puts them at greater risk of further abuse just for being diagnosed the way they are, even if they've never hurt a fly.

In short:

“Are you saying that murderers are right in the head??”
No there’s definitely something wrong with someone’s way of thinking if they can justify killing innocent people, but this doesn’t necessarily mean that they have a mental illness.
Extremist beliefs isn’t a mental illness.
Bigotry isn’t a mental illness.
Entitlement isn’t a mental illness.
Hate isn’t a mental illness.
Having a dysfunctional moral compass isn’t a mental illness.
We need to stop categorizing all these things as some undefinable “mental illness” and start looking at what we do as a society to develop and justify these things to a degree where people use them to justify killing.
Yes!
Dehumanization is something you Have to look for. If the murderer doesn’t see the person they killed as a person, then mental illness is probably not the main factor there.
Plenty of people murder women, poc, lgbt people, people of other religions etc. because they don’t see them as people.
Think about genocides - they aren’t perpetrated by big group of people/a government who all got mentally ill together the same way at the same time somehow, they just didn’t consider what they did murder because they didn’t see the victims as people.

Source

In more depth:
https://www.zillennialmag.com/post/when-narcissism-becomes-an-ableist-way-of-discussing-toxicity