I have a php 7.4 script that downloads a zip file using cURL. Both servers are
Apache/2.4.51 (Fedora)
Fedora 35
OpenSSL version 1.1.11
If I use CURL_HTTP_VERSION_1_0 all works. CURL_HTTP_VERSION_2_0 does not. Apache on the server I am calling has protocol h2 set. Below are the pertinent lines of code.

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0); // this is where I change to ver 2
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1) Gecko/20061024 BonEcho/2.0");

$html = curl_exec($ch);

the error I get using CURL_HTTP_VERSION_2_0 is Curl Error: transfer closed with 4 bytes remaining to read

Also, I can successfully cURL from the cli to the server from the same box the script is on with --http2.

What else should I try? Is there other info I should post to help answer?

EDIT: Is it possible the Content-Length header is being incorrectly set on the sending side?