It's worse than email, because emails at least almost always have subjects and the latest one usually contains most (if not all) of the thread. Email clients usually have a feature to save a message to some kind of file, and I usually attach that when creating a ticket (or working with one I didn't create).
My experience with Slack/Teams is like team using one email thread with the subject "team stuff" that they constantly reply to with fragmentary messages that are very difficult to decipher without full understanding of the context at that moment. Everything's jumbled together and impossible to piece together later.
IMHO, chat is only for things that are 100% ephemeral, and if there's any chance you will need the information later, you better immediately switch to email and summarize the previous conversation in complete sentences.