I often (sans COVID rules) interact with authors at conferences and also online and, unfortunately, I repeatedly hear the same old horror stories.
There are many "publishers" and/or "agents" who prey upon unknowledgeable or inexperienced authors. These authors end up locked in horrible contracts, they lose their copyrights, and/or get caught up in a financial scheme and are bilked out of a big chunk of change.
To protect themselves, I recommend that all authors hire a literary attorney to review all potential contracts. If they can't afford a literary attorney, at a minimum, they should do their due diligence and research all publishers prior to signing a contract. One place to easily research agents and publishers is Writer Beware. Writer Beware regularly reports on predator agents and publishers and anyone can use this information free of charge. You can find their website here: https://www.sfwa.org/other-resources/for-authors/writer-beware/
Remember that a traditional publisher will never ever charge an author a fee to publish a book. So, do yourself a favor, and do your research!