Since the update on Moodle 3.5.2 from 3.5 a lot of autolinks in activities on other activities are gone. After a while it was clear that only the autolinks on activities that had question a mark or exclamation marks at the end where broken.

Steps to reproduce:

In a course set the filter 'autolink on activities' -> on

Create a task where the title ends with a punctuation mark

Example: Which material is suitable?

Create a second task with a title: Build an alarm system

In the description to that task copy the title of the first task ;  save and look at the description

It should be a link to the first task but is only plain text.

Delete the punctuation mark in the title of the first task

Look at the description of the second task -> the Text is now a autolink and the punctuation mark at the end is plain text