rsyslog udp forwarding truncates at 2048 characters

Solution 1:

UDP doesn't have sequence numbers, there would be no way to combine messages coherently (if they arrive out of order)

Syslog UDP Transport - https://www.rfc-editor.org/rfc/rfc5426

3.1. One Message Per Datagram

Each syslog UDP datagram MUST contain only one syslog message, which MAY be complete or truncated. The message MUST be formatted and truncated according to RFC 5424 [2]. Additional data MUST NOT be present in the datagram payload.