Ajax Error after scheduling newsletter

Hi there,

Whenever i schedule a newsletter i recieve an ajax error:

/wp-admin/admin-ajax.php 413 (Payload Too Large)

The request comes well to the server and the newsletter is scheduled but the answer from mailpoet via ajax is way to large.

In case you are interested my filesize limits are large enough:

### WordPress Environment ###

WordPress address (URL): xxx
Site address (URL): xxx
WC Version: 8.5.2
REST API Version: ? 8.5.2
WC Blocks Version: ? 11.8.0-dev
Action Scheduler Version: ? 3.7.1
Log Directory Writable: ?
WP Version: 6.4.3
WP Multisite: –
WP Memory Limit: 512 MB
WP Debug Mode: –
WP Cron: –
Language: de_DE
External object cache: –

### Server Environment ###

Server Info: Apache
PHP Version: 8.1.27
PHP Post Max Size: 2 GB
PHP Time Limit: 600
PHP Max Input Vars: 5000
cURL Version: 7.29.0
NSS/3.90

SUHOSIN Installed: –
MySQL Version: 5.7.44-log-cll-lve
Max Upload Size: 2 GB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?

Any idea what to tweak?

Thanks,
Paul