I've seen concurrency in excess of 500 from Metas crawlers to a single site. That site had just moved all their images so all the requests hit the "pretty url" rewrite into a slow dynamic request handler. It did not go very well.
I was hoping they would extend it for a bit longer, not because I want to be running old versions but because 3.0/3.1 have some massive performance regressions that are yet to be fixed.
Have a look at HAProxys latest release announcement for some openssl 3.x commentary.
With some luck they will get a handle on this before 1.1.1 expires.