Automator selected the text character limit

I have an Automator workflow configuration that takes the selected text, performs processing and generates results. This works well for small entries. However, if I select more than 1000 characters, the workflow does not receive any input.

As a context, what I am trying to achieve is to describe a UML diagram in text, to code this text and to generate 2 links to an external service based on the coded chain. One to one image and one to an edit link respectively. These diagrams can be quite large and easily cross the threshold of 1000 characters.

I can not find any documentation on the existence of this limit and I found it only through tests. If someone knows the existing documentation, possible alternative solutions or ways to change this limit. I would be very interested to learn from them.