A lot more people identify with LGBT+ than there used to be, because it’s a very open label and people are more able to identify with it in accepting environments.
There’s a hell of a lot more people now who are… pretty much cishet, but maybe have some 5% attraction to the same sex, or they’re attracted to trans/nonbinary people, and so they consider themselves bisexual or pansexual, etc. when 5-10 years ago they probably wouldn’t have.
The specific number starts to mean a lot less when we remember the attitude of those people answering “do you identify with LGBT” has quickly shifted from “oh, well I’m definitely not gay!!” to “uhh sure, why not?” in a very short amount of time. I’m of the opinion this doesn’t reflect a change in our baseline behavior and is… not even consistently measurable given the diverging, shifting cultural context.